Fighting has resumed in Uganda after the collapse of a cease-fire agreement designed to open the way to formal peace talks.

The Ugandan military says rebels from the Lord's Resistance Army ambushed an army vehicle early Saturday, near the northern town of Gulu.

Ugandan President Yoweri Museveni ordered the army to resume attacks against rebel forces after a temporary cease-fire ran out Friday night. But the president also left open the possibility of future negotiations.

Both sides were expected to sign a wide-ranging truce on Friday, following a series of meetings this week. But the deal was delayed after rebels asked for more time to study the proposal.

The Lord's Resistance Army has been fighting to overthrow the Ugandan government since 1987, displacing more than one million people in the north. The rebels routinely attack civilians and kidnap children for forced labor as soldiers and sex slaves.