A pilotless US drone aircraft fired a missile in northwest Pakistan on Saturday, killing 13 people including some foreign militants, security officials and residents said.

The attack was in the North Waziristan region, a stronghold of al Qaeda and Taliban militants on the Afghan border, in an area 35 kilometres west of the region's main town of Miranshah at about 3 am, they said.

"The missile hit a house where some guests were staying," one intelligence agency official said, referring to foreign militants. "We have information that 13 people were killed including some guests," said the official, who declined to be identified.

One resident, Amir Shah, said drones were still flying over the area several hours after the attack.

Many Al Qaeda and Taliban militants fled to northwestern Pakistani border regions such as North Waziristan after US-led forces ousted the Taliban in Afghanistan in late 2001.

From the remote ethnic Pashtun tribal lands that have never been governed by any Pakistani government, the militants have orchestrated the Afghan war and plotted violence beyond.

With the Afghan insurgency intensifying, the United States began launching more drone attacks on the Pakistani side of the border last year.

Since then, about 35 US strikes have killed about 350 people, including mid-level Al Qaeda members, according to reports from Pakistani officials, residents and militants.

Pakistan objects to the strikes, saying they are a violation of its sovereignty and are counter-productive.

Officials say about one in six of the strikes over the past year caused civilian deaths without killing any militants, and that fuels anti-US sentiment, complicating the military's struggle to subdue violence.

The concentration of strikes in Waziristan was also pushing some militants eastwards, deeper into Pakistan, they say.-Reuters