The Foreign Ministry took issue with U.N. Special Representative Kai Eide, who recently issued a list of reforms that he expected Karzai to make. Such comments 'exceeded international norms' and 'violated respect for Afghanistan's national sovereignty,' the ministry said in a statement. In an incident that could exacerbate tensions between Karzai's government and the West, international and Afghan forces were investigating Saturday whether a NATO airstrike in the northwest of the country killed eight Afghans and injured 22 people, including five U.S. troops. The casualties, most of them Afghan soldiers and policemen, occurred during a joint manhunt for two U.S. paratroopers missing since Wednesday. At a news conference Thursday, Eide warned Karzai that he risked losing the support of international donors and troops unless he cleansed his government of corruption and warlords. 'We can't afford any longer a situation where warlords and power brokers play their own games,' Eide said. 'We have to have a political landscape here that draws the country in the same direction, which is in the direction of significant reform.' President Barack Obama and British Prime Minister Gordon Brown have made similarly pointed remarks since Karzai was declared the winner Monday of a drawn-out election tainted by fraud. Both leaders need a credible partner in Kabul to justify sending additional troops to fight an escalating Taliban insurgency. 'Over the last few days, some political and diplomatic circles and propaganda agencies of certain foreign countries have intervened in Afghanistan's internal affairs by issuing instructions concerning the composition of Afghan government organs and political policy of Afghanistan,' the Foreign Ministry statement said. It noted that Karzai has pledged to make the fight against corruption and other reforms a top priority of his next administration. 'Without doubt, consultation and discussion ... is essential,' the statement said. 'However, it is necessary to ensure respect for Afghanistan's national sovereignty.' Dan McNorton, a spokesman for the U.N. mission in Afghanistan, said its mandate was to 'support and also to advise the government.' 'Of course, some of that advice is going to be unpalatable,' he said. Also Saturday, Afghan security officials said four of their soldiers and three policemen were killed when NATO aircraft mistakenly targeted international forces in the Bala Murghab district of Badghis province. An additional 14 soldiers and two policeman were injured, they said. The NATO force confirmed the casualties and said it was investigating with Afghan authorities whether some of them may have been caused by friendly fire. An Afghan civilian interpreter was killed and another wounded along with five Americans during the operation, which involved multiple firefights over several hours Friday, said U.S. Air Force Lt. Col. Todd Vician, a spokesman for the NATO-led coalition in Afghanistan. The clashes occurred as Afghan and international forces were searching for the two paratroopers who disappeared while trying to recover airdropped supplies from a river. Police said they were swept away in the current. Abdu Raouf Ahmadi, spokesman for the western regional police command, said the joint forces were pursuing Taliban insurgents in a village when the airstrike happened Friday. He was not certain, however, whether fighting was going on at that moment. 'I think it was just a misunderstanding,' Ahmadi said. 'They didn't know that there were Afghan and foreign forces in the village.' Defense Ministry spokesman Mohammed Zahir Azimi confirmed that the Afghan casualties were the 'result of NATO bombarding.' 'We are saddened by the loss of life and injuries sustained during this very important mission,' U.S. Navy Capt. Jane Campbell, a coalition spokesman, said in a statement. The search for the missing paratroopers from the 82nd Airborne Division, based at Fort Bragg in North Carolina, continued Saturday. Such disappearances are rare. The last time a U.S. service member went missing in Afghanistan was in June, when Pfc. Bowe R. Bergdahl was captured after straying from a base near the eastern border with Pakistan. On July 18, Taliban insurgents released a video of the 23-year-old soldier from Idaho. He has not been found. Special correspondent Karim Sharifi contributed to this report. 