A man in an Afghan police uniform shot and killed a U.S. service member Sunday, a U.S. Defense Department official said, raising the death toll to 10 in such attacks in just two weeks.

The surge in violence by Afghan allies against their international partners has raised doubts about the ability of the two forces to work together at a key transition time. Afghan forces are expected to take over security for the country by the end of 2014, when most of the international combat forces are scheduled to leave.

On the other side, a coalition airstrike killed dozens of Taliban militants, including one of their leaders, officials said.

The U.S. defense official in Washington discussed the matter on condition of anonymity because the official notification process had not been completed.

Few details were immediately available about Sunday's killing of a coalition member in southern Afghanistan. NATO said only that they and Afghan authorities were investigating. Afghan officials could not be reached for comment.

advertisement | advertise on newsday

The Taliban have been actively recruiting members of the Afghan security forces, saying in a statement last week that they considered these turncoat attacks a major part of their strategy against international forces.

Once an anomaly, these attacks have been climbing in recent months. There have been 30 of the kind reported so far this year, up from 11 in 2011.

On Saturday Defense Secretary Leon Panetta called Afghan President Hamid Karzai to encourage him to work with U.S. commanders to ensure more rigorous vetting of Afghan recruits.