NATO said two U.S. soldiers have been killed in a bomb blast in southern Afghanistan.

The NATO-led force released no other details of the incident. The U.S. military confirmed the soldiers were American.

July has been the deadliest month for international forces in Afghanistan since the Taliban-led government was ousted in 2001.

In recent weeks, 4,000 U.S. Marines, along with British and Afghan troops, have launched a major offensive in southern Afghanistan, targeting Taliban insurgents in their traditional strongholds.

The operation is aimed at ensuring security ahead of Afghanistan's presidential election next month.