U.S. drone missile strikes have killed at least twenty people in North Waziristan, the wild tribal region of Pakistan that borders Afghanistan and is reportedly a haven for terrorist groups.

Pakistan security officials said the missiles struck a militant training camp in the Shawal area and that all the casualties were fighters loyal to Pakistani warlord Hafiz Gul Bahadur.

Bahadur’s forces have been blamed for insurgent attacks on NATO troops in neighboring Afghanistan.

“The death toll is 20. It is likely to go up,” a senior security official told Agence France Presse.

He added that the dead men might have included foreign militants as well fighters from

The Haqqani terrorist network, which is connected to al Qaeda, is also believed to be based in the remote, heavily forested Shawal area.

Over the weekend, another US drone strike struck in South Waziristan, killing prominent al-Qaeda militant, Ilyas Kashmiri.

On Monday, three separate drone strikes killed at least 18 people in South Waziristan.

The US government does not confirm its drone strike activities. Pakistanis have long complained that the missiles have killed civilians, instead of the militants they are supposed to target.