Police retrieved video footage from a damaged vehicle at the scene, showing two teenagers wearing suicide jackets. — Reuters

CHARSADDA, Pakistan A suicide bomber blew up a vehicle packed with explosives at a police checkpoint in northwest Pakistan, killing 18 police and civilians, officials said Thursday.

Pakistan security troops are frequent targets for extremist militants who oppose the governments alliance in the US-led `war on terror` and more than 1,500 government forces have been killed by insurgents since 2002.

The bomber blew up his vehicle late Wednesday in Charsadda, just north of Peshawar in the North West Frontier Province.

`Police were searching a vehicle when a mini-truck came and blew up,` senior police official Sefwat Ghayour told AFP.

`Bodies of two civilians were found near the site of the attack, raising the death toll in the attack to 18,` local police official Nasrullah Khan told AFP.

Khan said seven policemen were wounded, two of them seriously. They were all taken to Peshawar for treatment, he added.

Hospital official Mohammad Ali confirmed 18 people were killed.

`We have received 18 bodies in our hospital,` Ali said, adding that the dead included nine police and nine civilians.

Police also retrieved video footage from a damaged vehicle at the scene, showing two boys wearing suicide jackets, who looked like teenagers. One recited from the Holy Quran and the second was shown smiling, said Ghayour.

`We cannot say at this stage whether the two boys were the attackers or someone else did it,` the police official told AFP.

There has been no claim for the attack and police have not been able to confirm the identity of the bomber.

Initial inquiries revealed that more than 200 kilograms of explosives were used.

Wednesdays blast left a large crater, shattered windows in nearby buildings and severed power cables, plunging the area into darkness.

Joint funeral prayers were said for five of the dead policemen, their bodies carried in wooden coffins wrapped in the national flag at police headquarters in Charsadda.

The large town has been scarred by several suicide bombings and is home to the chief of the ruling Awami National Party, Asfandyar Wali Khan, who narrowly escaped a suicide attack last year.