A US drone strike has killed at least four suspected fighters in a restive northwestern Pakistani tribal area on the Afghan border, officials have said, taking the death toll from a flurry of such strikes this week to 25.

The attack took place on Thursday at Laman village in North Waziristan where the Pakistani military has been waging a major offensive since June.

"A US drone fired two missiles at a vehicle and killed at least four militants and one was wounded," a senior security official told the AFP news agency.

The official said that the strike took place before midnight and added that there were "foreigners" among those killed. A local government official confirmed the casualties.

There has been a spike in drone attacks in North Waziristan this month. Analysts say it could be linked to intelligence regarding a high-value target, though none of the casualties so far have been named.

Major offensive

The semi-autonomous tribal region has for years been a hideout for armed groups of all stripes - including al-Qaeda and the Tehreek-e-Taliban Pakistan (PTT), as well as foreign fighters such as Uzbeks and Uighurs.

Washington pressed Islamabad for years to destroy sanctuaries in the area, which fighters have used to launch attacks on NATO forces in Afghanistan.

The army launched a major offensive against the rebels in North Waziristan in June, and say they have killed more than 1,000 so far, with 86 soldiers losing their lives in the operation.

The PTT dispute the army's figures for the number of fighters killed.

The area is off-limits to journalists, making it impossible to verify the number and identify the dead independently.

Pakistan routinely protests against US drone strikes, which have been targeting fighters in the tribal areas since 2004, saying they violate its sovereignty and are counterproductive in the fight against terrorism.

But most analysts believe the resumption of the drone programme after it was suspended - reportedly to give Pakistan space for negotiations with the Taliban which ultimately failed - is evidence of collusion between the two countries.

Source: Agencies