KABUL, Afghanistan — NATO mistakenly killed five of its Afghan army allies in an airstrike today while they were attacking insurgents in the country's east, officials said.

Three American soldiers also were reported killed in a roadside bombing in the south.

The Afghan soldiers were launching an ambush before dawn against insurgents reportedly on the move in Ghazni province when NATO aircraft began firing on them without warning, Afghan Defense Ministry spokesman Gen. Mohammad Zahir Azimi said.

Also NATO said three American troops were killed by a roadside bomb in the south Tuesday. It did not identify them or give any other details.

Last month was the deadliest for international forces since the war began, with 103 killed, including 60 Americans.