KABUL — A Taliban ambush that appears to have had inside help killed up to 24 Afghan security forces in southern Afghanistan early Friday, officials said.

It was the latest Taliban assault on government forces since the militant group signed a peace agreement with the United States on Feb. 29. The Taliban have so far ceased attacks against American and coalition troops, but they have continued to target Afghan government forces.

A group of Taliban fighters attacked a joint police and army outpost around 3 a.m. Friday on the main highway to Kabul in Zabul Province, parts of which are under the militants’ control. Rahmatullah Yarmal, the governor of Zabul Province, said the attackers were aided by at least five police officers who then escaped with the Taliban fighters.

The attackers burned the outpost after killing every man inside, said Haji Malim Kareem, a tribal elder from Qalat, the provincial capital.