MIRANSHAH, Pakistan, (Reuters) – A suicide bomber rammed his explosive-laden car into a Pakistani security force checkpost in the North Waziristan tribal region on Friday, killing two policemen, security officials and a doctor said.

The attack occured near Mir Ali, a town known as a sanctuary for al Qaeda militants. A senior al Qaeda leader, Abu Laith al-Libi, was killed in a missile attack in the area, apparently fired by a U.S. drone this week.

A doctor at the government hospital in Miranshah, the region’s main town, said the bodies of two policemen and 10 wounded men had been brought in.

Violence has intensified in northwest Pakistan in recent weeks with militants attacking security forces, who have mounted counter-attacks in response.

Many al Qaeda members and Taliban militants took refuge in semi-autonomous tribal lands on the Pakistani side of the border after U.S.-led forces