WASHINGTON — The Bush administration is telling a federal appeals court that it has the authority to detain a Canadian who was captured in Afghanistan when he was 15 and is accused of killing a U.S. soldier.

Attorneys for Omar Khadr, who is being held at the U.S. military prison in Guantanamo Bay, say international law bars governments from detaining people that young as enemy combatants and prosecuting them for war crimes.

The government, in a filing Friday with the U.S. Court of Appeals for the District of Columbia Circuit, says the military has the authority on the battlefield to capture and detain anyone, including juveniles, attacking and killing U.S. soldiers.

The court will hear arguments in the case on Sept. 4.