PESHAWAR ? Islamist militants blew up a girls' school in Pakistan's Khyber district on Thursday, the second such attack in the lawless region on the Afghan border in four days, officials said.

"Militants used 25 to 30 kilograms (55 to 66 pounds) of explosives to blow up the two-storey school on the outskirts of Bara town," local administration official Farooq Khan told AFP.

Khan said the school had 26 rooms in all, including a science laboratory, adding that the explosion completely destroyed eight rooms.

Another senior administration official Shafeer Ullah confirmed the incident.

The new attack came four days after twin bombs ripped through an 18-room government high school for girls at Kari Gar village in Khyber wounding four people in neighboring homes.

Islamist militants have destroyed hundreds of schools, mostly for girls, in the northwest of the country in recent years.

Nearly 200 schools were destroyed in the Swat valley alone during a two-year Taliban uprising to enforce sharia law in a district once favored by Western tourists for its ski slopes and bracing mountain air.

Following up a similar offensive in Swat this summer, Pakistan has been fighting against homegrown militants in Khyber and pressing a major assault designed to crush Taliban sanctuaries in South Waziristan.

Authorities last month shut schools across Pakistan following a suicide attack on a university campus in Islamabad, although most have since reopened.