Amid a rising number of causalities for US forces in Afghanistan, two separate bomb attacks have claimed the lives of three more American troops in the volatile country.

The NATO-run International Security Assistance Force (ISAF) said that two of the soldiers were killed in an attack in eastern Afghanistan on Friday, while another was killed in the south of the country the same day.

"Two US service members were killed in an improvised explosive device (IED) attack in eastern Afghanistan on October 16, and one US service member was killed in an IED attack in southern Afghanistan on the same day," ISAF said.

The incidents come just a day after four American soldiers were killed in a bomb explosion in southern Afghanistan.

This year has been the deadliest for NATO troops in Afghanistan since the US-led invasion in 2001.

More than 400 international forces have been killed in the war-torn country in 2009.

JR/SS/MMA