Blast outside school in Afghanistan kills 25

By Hamid Shalizi and Paul Tait

KABUL (Reuters) - An explosion outside a school south of the Afghan capital on Thursday killed at least 25 people, including 15 students, officials said, and Taliban fighters overran a district near the Pakistan border after heavy fighting.

The blast in Logar province and the gunbattles in eastern Nuristan were the latest incidents in an escalation of violence across Afghanistan since U.S. Marines launched a major new offensive in the Taliban bastion of Helmand a week ago.

That assault, Operation Strike of the Sword, is the first major operation under U.S. President Barack Obama's new regional strategy to defeat the Taliban and stabilise Afghanistan, which holds a presidential election on August 20.

Afghanistan's east and south have long been Taliban strongholds, although a growing insurgency has spread out of those areas in recent months to the relatively safer north and even to the outskirts of Kabul.

Officials said the Logar blast was caused by explosives hidden beneath a pile of firewood in the back of a truck which had crashed overnight, leading to speculation the explosives could have been meant for an attack elsewhere.

Logar police chief Ghulam Mustafa said the truck rolled into a stream between two schools. The blast went off as police checked the abandoned truck in the morning, he said.

"The four police who were checking the truck got killed, so were the students and some shopkeepers and other civilians," Mustafa told Reuters by telephone.

He said the explosives were possibly being taken by Taliban insurgents to Kabul for a planned attack there.