PESHAWAR (Pakistan) - HUNDREDS of militants, many from Afghanistan, attacked a Pakistani paramilitary camp in a lawless northwestern tribal region, sparking a major clash that left six security troops and 40 insurgents dead.

The brazen raid on Sunday in Mohmand suggested sophisticated cross-border coordination among Taleban militants nesting in Afghanistan and Pakistan and underscored the continued strength of the militancy despite a continuing Pakistani military offensive.

Insurgents attacked the Pakistani Frontier Corps' camp at about 2 am (5am Singapore time) with mortars and rockets, then used small arms to fire on a checkpoint near the Mohammad Ghat camp, said a paramilitary official, who gave details on condition of anonymity because he was not permitted to comment to the media.

The 600 or so attackers were eventually driven off, but scattered skirmishes continued, he said.

The official said the bulk of the militants crossed over from Afghanistan and later joined with Pakistani allies. He said it was unclear when the Afghan-based militants came over. He described them as foreigners, which could also include Arabs, Uzbeks and other insurgents.

At least 40 militants were killed and scores were wounded, while six security forces died and seven were hurt, according to the official and a Frontier Corps statement.

Segments of Pakistan's semiautonomous tribal belt are considered strongholds of al-Qaeda and Taleban fighters, many of whom are believed to be involved in attacks on American and Nato troops in Afghanistan. Militants frequently crisscross the porous border.

Pakistan has deployed more than 100,000 troops in its northwest to battle the militant threat, and in summer 2008, it rolled out a major offensive in the Bajur tribal region that has spread south into Mohmand as well.

Pakistan says it has killed more than 1,700 insurgents in the offensive, which the US has praised for helping reduce violence on the Afghan side.

The US remains deeply concerned about militants finding safe havens in Pakistan, and it has stepped up its own campaign of missile strikes on militant targets primarily in the tribal belt.

Access to the remote, dangerous mountain region is severely restricted, making it near impossible to independently verify the account of Sunday's attack.

Also on Sunday, purported Taleban fighters abducted five members of an anti-militant tribal committee in Bajur and sliced an ear off each, said local government official Israr Khan.

One victim told police at a hospital that the abductors warned them they would slash off their tongues and remaining ears if they maintained their anti-militant activities, Mr Khan said. -- AP