(REUTERS) - Two NATO soldiers were shot dead on Thursday by two Afghans, including a man believed to be a soldier, NATO said, an attack that is likely to raise further questions about the future of the country's security forces.
A supporter of the Pakistan Tehreek-i-Insaf (Pakistan's Movement for Justice) shouts anti-U.S. slogans during a rally in Peshawar March 1, 2012.
The killings in south Afghanistan came after two senior U.S. officers were gunned down in the heart of Afghanistan's Interior Ministry on Saturday by what Afghan security officials say was a police intelligence official.
That attack raised questions about NATO's strategy of replacing large combat units with advisers as the alliance tries to wind down the war.
NATO immediately moved to withdraw all its advisers from Afghan ministries, followed by Britain, Germany and Canada.
At least five NATO soldiers have been killed by Afghan security forces since the burning of copies of the Koran at a NATO base last month triggered widespread protests.
According to the U.S. Pentagon, around 70 members of the NATO force were killed in 42 insider attacks from May 2007 through January 2012.
These incidents have become more frequent as the United States has sent tens of thousands of more soldiers to Afghanistan as part of a surge to fight in Taliban strongholds.
The United States hopes Afghan security forces will be able to confront the Taliban and handle security on their own before NATO combat troops' scheduled departure by the end of 2014.
Attacks by Afghan forces on NATO troops have deepened doubts about their capabilities.
A senior Ministry of Defence official told Reuters on Wednesday that Afghanistan must act quickly to tackle infiltration of its security forces or another attack on Western forces could undermine ties with NATO.