Islamabad - A bombing outside a courthouse in north-western Pakistan on Wednesday killed at least one person and wounded three, police said.

The explosion took place in a parking lot adjacent to courtrooms in Dera Ismail Khan, located close to Pakistan's lawless tribal region near the Afghan border.

"A police constable deployed in the parking bay was killed, and three civilians were injured," said Gul Afzal Khan Afridi, the district police chief. Several cars were damaged in the blast.

Afridi said a preliminary investigation suggested the explosive device was detonated by remote control. It was not immediately known whether the bomb was planted in a vehicle or left at the site.

Dera Ismail Khan has witnessed a spate of attacks in recent weeks. Most have been linked to the sectarian strife between majority Sunni and minority Shiite Muslims.

The city also borders the South Waziristan tribal district, a stronghold of top Taliban commander Baitullah Mehsud.

Pakistan's government announced last month that troops had been asked to eliminate Mehsud and his network. Although dozens of airstrikes and shelling campaigns have been carried out since then, a full-fledged ground offensive has yet to begin.

Mehsud carries a 5-million-dollar US bounty on his head for being "a key al-Qaeda facilitator" and tops Pakistan's list of most-wanted terrorists. (dpa)