SYDNEY The hunt for missing Malaysian Airlines Flight MH370 is on track to cost hundreds of millions of dollars, becoming the most expensive search in aviation history with 26 countries contributing planes, ships, submarines and satellites to the international effort. 
 
 A month into the search for the jet, estimates compiled by Reuters show that at least $44 million has already been spent on the deployment of military ships and aircraft in the Indian Ocean and South China Sea by Australia, China, the United States and Vietnam. The figure is based on defense force statistics on available hourly costs of various assets, estimates by defense analysts and costs reported by the Pentagon. 
 
 The figure for the first month of the search is already about equal to the official 32 million euros ($44 million) spent in searches lasting several months spread over a two-year time frame for Air France's Flight AF447, which crashed into the Mid-Atlantic in 2009. 
 
 Just as salvage experts said the actual costs for the Air France operation could have been three or four times higher than the official figure, the bill for the current search is expected to run into hundreds of millions of dollars. 
 
 The $44 million estimate for MH370 does not cover all the defense assets being used by countries including Britain, France, New Zealand and South Korea, nor numerous other costs such as civilian aircraft, accommodation for hundreds of personnel and expenses for intelligence analysts worldwide. 
 
 Britain dispatched a nuclear-powered submarine, HMS Tireless, to assist in the search, without disclosing the vessel's previous location. 
 
 Angus Houston, the retired Air Chief Marshal in charge of the Australian-led international search, said on Friday he would give an overall estimate of the cost at a later date. 
 
 "It's a lot of money," he said. 
 
 A FINANCIAL RECKONING 
 
 Australian Prime Minister Tony Abbott, whose country is leading the search, and his Malaysian counterpart, Najib Razak, have repeatedly said the cost of the search is not an issue. 
 
 Still, Abbott has hinted that Australia, which has so far borne the brunt of the expense as the search homes in on the southern Indian Ocean off its western coast, may at some point be sending out invoices. 
 
 "It's only reasonable that we should bear this cost - it's an act of international citizenship," Abbott said last week. 
 
 "At some point, there might need to be a reckoning, there might need to be some kind of tallying, but nevertheless we are happy to be as helpful as we can to all the countries that have a stake in this." 
 
 A Malaysian government source, who declined to be identified as he was not authorized to speak to the media, said the entire search and recovery for MH370 could be at least double the money spent to recover the black box from Air France's AF447. 
 
 Australia has so far contributed around half of the cost, with ships and aircraft on duty for some three weeks. Its HMAS Success alone costs around A$550,000 ($511,000) a day to operate, according to Australian Defence Force, or ADF, figures. 
 
 "The search effort for MH370 is costing the ADF at least A$800,000 per day and possibly considerably more than that," said Kym Bergmann, editor of Asia-Pacific Defence Reporter and a former government defence adviser. 
 
 "While that might not sound like much compared with the ADF's annual sustainment budget of A$5 billion, if this continues for much longer other activities such as 'Operation Sovereign Borders' will be under pressure to find savings," he added, referring to the federal government's policy of turning back asylum seeker boats that approach from Indonesia. 
 
 CHINA, U.S. SPENDING 
 
 The other big spenders so far are China and the United States. 
 
 China, which was home to the majority of the 227 passengers on board the missing plane, has sent a total of 18 ships, eight helicopters and three fixed-wing aircraft to various search areas during the month-long hunt. 
 
 Beijing has declined to comment on how much it is spending on looking for the aircraft, saying only it is dedicated to keep searching "as long as there is a shred of hope". 
 
 China has been sending two Ilyushin Il-76 aircraft, on alternate days, on sorties from RAAF Pearce Base near Perth for almost three weeks. The Global Times, an influential tabloid published by the ruling Communist Party's official People's Daily, estimated that an Ilyushin Il-76 costs $10,000 an hour to keep in the air on fuel alone, not including money spent on maintenance or accommodation for the crews. 
 
 Chinese warships would cost at least $100,000 a day to operate, and most likely a lot more, the newspaper added. 
 
 "There's a lot of pressure in China to find the plane," said a Beijing-based Western diplomat. "China will spare no effort." 
 
 The Pentagon said last week that it had already spent more than $3.3 million on the search and has put in place plans to nearly double its original $4 million budget. 
 
 As well as flying its P-8 surveillance planes out of Perth, the U.S. Navy is playing an instrumental role via its high-tech underwater black-box detector equipment. 
 
 It has sent both its Towed Pinger Locator, which this week picked up signals which may be from the missing plane's cockpit data recorders, and a Bluefin-21 autonomous underwater vehicle. 
 
 An earlier search in the South China Sea by Vietnam was estimated by local media to cost $8 million, a figure that has not been verified by officials. 
 
 ($1 = 1.0759 Australian Dollars) ($1 = 0.7303 Euros) 
 
 (Additional reporting by Niluski Koswanage in KUALA LUMPUR, Ben Blanchard in BEIJING, Swati Pandey in PERTH and Mai Nguyen in HANOI; Editing by Lincoln Feast and Kenneth Maxwell) ||||| This map provided by the Joint Agency Coordination Center shows details in the search for the missing Malaysia Airlines Flight 370 in the southern Indian Ocean. (Joint Agency Coordination Center / ) 
 
 Private companies specializing in deep ocean search will be hired to continue the quest to find Malaysia Airlines Flight 370, Australia’s prime minister said Monday, and the cost could run more than $55 million and take six to eight months. 
 
 The U.S. Navy’s robotic submarine Bluefin-21 has searched more than 150 square miles of the floor of the Indian Ocean in an area where investigators thought they had detected pings from the Boeing 777’s black box transmitters in early April. We are “baffled and disappointed” that no wreckage had been found 52 days into the search, Prime Minister Tony Abbott said at a news conference in Canberra, Australia. 
 
 Now, Abbott said, the undersea search area will be expanded from the most probable impact zone to a much wider area totaling 21,621 square miles. 
 
 Side-scan sonar devices towed behind ships will be used to traverse the expanded search area, said retired Australian Air Chief Marshal Angus Houston, who has been coordinating search efforts from Perth, Australia. 
 
 Abbott indicated that air searches for surface debris would be discontinued imminently. “It is highly unlikely we will find any debris on the ocean surface” now, he said, explaining that any material from the plane probably would have become waterlogged and sunk by this time. 
 
 “We are moving to a phase focused on searching the ocean floor over a much larger area,” Abbott said. So far, the visual search area has encompassed 334 flights totaling more than 3,000 hours and scoured 1.7 million square miles of the ocean surface. 
 
 Until the private companies can begin working, Abbott said, the Bluefin-21 as well as Australian, Malaysian and Chinese ships will continue operating in the search area. An Australian military plane will remain on standby in case suspected wreckage is identified, he added. 
 
 “I want the families to know, I want the world to know, Australia will not shirk its responsibility,” Abbott said. “We will not let people down.” 
 
 Asked about his comments several weeks ago that investigators were close to finding the wreckage, Abbott said he was “not in the business of making excuses for failure” but added that the search was perhaps the most difficult in history. 
 
 “Enormous efforts have been made,” he said, describing the jet’s disappearance as an “extraordinary mystery.” 
 
 Houston said investigators believe they are looking in the right area. “We were quietly optimistic,” he said, that the Bluefin-21 would find the jet wreckage. 
 
 But he noted that it took more than two years to find the undersea wreckage of Air France Flight 447 in the Atlantic Ocean after it crashed in 2009, and that in that case, the plane was found just 6.5 nautical miles from its last known position. Data about the last known position of Malaysia Airlines Flight 370 is much less robust. 
 
 Asked about the cost of the search so far, Abbott declined to provide specifics, saying authorities had been using military assets that governments would be “paying for anyway.” 
 
 The Boeing 777 vanished March 8 en route from Kuala Lumpur, Malaysia, to Beijing with 239 people aboard. Authorities have said they believe a deliberate act by someone aboard the aircraft led to its disappearance, but they have not offered more specifics.
– As searchers listen for pings in the Indian Ocean that might help them find the missing Flight 370, Reuters assesses the cost of the hunt after a month and finds that it's on track to become the most expensive search in aviation history. Reuters figures that the militaries of Australia, China, the US, and Vietnam have spent $44 million already, about the amount spent in the two-year search for the Air France jet that went missing in 2009. The $44 million total doesn't take into account civilian aircraft or the cost of accommodating hundreds of intelligence analysts and other personnel worldwide. Add those expenses in, and the total is in the "hundreds of millions of dollars." Australia is leading the search and has borne about half the costs so far, though Prime Minister Tony Abbott said the nation may ask others to defray its expenses later. "At some point, there might need to be a reckoning, there might need to be some kind of tallying, but nevertheless we are happy to be as helpful as we can to all the countries that have a stake in this," he said. The Pentagon estimates that the US has spent $3.3 million so far. With no sign of the pings in two days, the search could drag on and on, reports AP. Australia plans to release a submersible to scan the ocean floor, but it hopes to get a more precise location before doing so.