French troops stand guard along the road leading from Markala to Niono, in Markala, approximately 40 km outside Segou, in central Mali, Wednesday, Jan. 16, 2013. French troops pressed northward in Mali toward territory occupied by radical Islamists on Wednesday, military officials said, announcing the start of a land assault that will put soldiers in direct combat "within hours." Mali army cadets secure a perimeter on the military side of Bamako's airport Wednesday Jan. 16, 2013, during a joined visit to French and Malian troops by Mali's President Dioncounda Traore and French Ambassador to Mali Christian Rouyer. In this picture released by the French Army Communication Audiovisual office (ECPAD) French armored vehicules drive to the north of Mali, outside Bamako, Wednesday, Jan. 16, 2013. Mali National Guard soldiers stand guard on the military side of Bamako's airport Wednesday Jan. 16, 2013, as a commercial jet takes off during a joined visit to French and Malian troops by Mali's President Dioncounda Traore and French Ambassador to Mali Christian Rouyer. French troops pressed northward in Mali toward territory occupied by radical Islamists on Wednesday, military officials said, announcing the start of a land assault that will put soldiers in direct combat "within hours." (AP Photo/Jerome Delay) BAMAKO, Mali (AP) - French soldiers pressed north in Mali territory occupied by radical Islamists on Wednesday, launching a land assault that was to put them in direct combat with al-Qaida-linked fighters "in one to 72 hours," military officials said. Their presumed destination was the town of Diabaly, where fleeing residents said Islamist extremists had taken over their homes and were preventing other people from leaving. They said the militants were melting into the population and moving only in small groups on streets in the mud-walled neighborhoods to avoid being targeted by the French. Everyone is afraid," said Ibrahim Komnotogo, who was out of town when the militants seized Diabaly over the weekend but kept in contact by telephone with other residents. In apparent retaliation for the French offensive, the same group controlling northern Mali occupied a natural gas complex in neighboring Algeria, taking dozens of people hostage, including Americans. Two foreigners were killed. French ground operations in Mali began overnight, France's military chief of staff, Adm. Edouard Guillaud, said on Europe 1 television Wednesday. He stressed that French infantry units "will be fighting directly in the coming hours." Armored vehicles loaded with French troops were seen heading toward Niono, a town 340 kilometers (210 miles) northeast of the capital, Bamako. Some 70 kilometers (45 miles) northeast of Niono lies Diabaly, with a population of 35,000. Over the weekend, dozens of rebel vehicles cut off the road to Diabaly, seizing the town and its strategic military camp. French warplanes have since carried out airstrikes on the camp. Oumar Ould Hamaha, whose fighters are believed to be among those who seized Diabaly, said that a convoy of armored French vehicles attempted to enter the town to take it back. He said the Islamists repelled the French after an intense and close combat. I confirm that France came in by land, but they failed. ... There was a combat that was (extremely close). Between 200 and 500 meters away," Hamaha said. His version of events could not be verified. Col. Thierry Burkhard, a spokesman for the French military in Paris, denied that French troops were in Diabaly or that they were 500 meters from rebel lines. "The French army did not deploy units in the region of Diabaly," Burkhard said. Troops were dozens of kilometers from Diabaly, he said, refusing to provide a location. Hamaha is a leader of the Movement for Oneness and Jihad in West Africa, one of the rebel groups controlling Mali's northern half. He is also a close associate of Moktar Belmokar, a leader of a local al-Qaida cell who claimed responsibility for the kidnapping of foreigners in Algeria. Speaking to The Associated Press by telephone from an undisclosed location, Hamaha said the kidnapping was retribution for the French-led attack on the Islamists in Mali. "We have a struck a blow to the heart (of the international community)," he said. It's the United Nations that gave the green light to this intervention and all Western countries are now going to pay a price. We are now globalizing our conflict. A former French colony, Mali once enjoyed a reputation as one of West Africa's most stable democracies with majority of its 15 million people practicing a moderate form of Islam. That changed in April 2012, when Islamist extremists took over the main cities in the country's north amid disarray following a military coup, and began enforcing strict Shariah law. Hamaha's boast comes amid warnings from security experts that the extremists, including al-Qaida in the Islamic Maghreb and other groups which share al-Qaida's goals, are carving out their own territory in northern Mali from where they can plot terror attacks in Africa and Europe. Estimates of how many fighters the Islamists have range from less than 1,000 to several thousand; the militants are well-armed and funded and include recruits from other countries. Despite training from U.S. and other Western advisers, the Mali army has been ineffective in fighting the militants. Last December, the U.N. Security Council passed a cautious resolution, outlining steps that needed to be taken before an international military intervention, one which diplomats said would not occur before at least September. But in a surprise move last week, French President Francois Hollande authorized airstrikes in Mali to stop a sudden southward push by three Islamist rebel groups, including Hamaha's. The Islamists warned that France had "opened the doors of hell" and that all French nationals would pay, as would any country that helped the military intervention. France's allies have offered vocal support for the country's military operation in Mali, but when it comes to sending troops or weapons, they are agreeing to the bare minimum: a transport plane here and there, a handful of support staff and a lot of promises to think about it. As the French moved north, some terrified Malians were fleeing south. A trickle of refugees have left Diabaly on foot over the past few days and went to Niono, according to residents there. It apparently was no easy task. Komnotogo, who heads a USAID-financed rice agriculture project, said Qaida-linked rebels sealed off Diabaly's roads and were preventing people from leaving. Komnotogo said he was last able to speak to most of his 20 employees and contractors on Tuesday - after which the telephone network was cut in Diabaly. He fears the Islamists are planning to hide and use the population as a human shield. They don't move around in big groups. ... They are out in the streets, in fours, and fives and sixes, and they are living inside the most populated neighborhoods," he said, explaining that they had taken over the homes of people who managed to flee before the road was cut off. Residents have evacuated the Diabaly neighborhood called Bordeaux, after its sister city in France, which is only 500 meters (yards) from the camp, Komnotogo said. They have moved mostly into a quarter called Berlin, about 1 kilometer (0.6 miles) from the military installation. The Islamists "are preventing the population from leaving. Tidiane Diarra, one of Komnotogo's employees, who distributes water to rice cultivators, arrived in Niono on Wednesday. He said he was able to escape because he was not in Diabaly but in his home village 4 kilometers (2.5 miles) away. From there, no one stopped him from leaving. The fighters, he said, are going to be difficult for the French to weed out, because they are now traveling inside the town on motorbikes, leaving their pickup trucks parked elsewhere. They appear to be melting into the population. The head of France's military said it is plausible that the extremists would be willing to hide behind civilians. Guillaud said the militant groups have a history of taking human shields and that France would do its utmost to make sure civilians are not wrongly targeted. He added that the French continued their airstrikes overnight on Tuesday to Wednesday. Targets destroyed so far include training camps, logistical depots, command centers and armored vehicles that the jihadists had seized from Mali's government forces. Associated Press writers Lori Hinnant in Paris , Aomar Ouali in Algiers, Algeria and Paul Schemm in Rabat, Morocco contributed to this report from Paris.