At least 16 security personnel were killed and eight others injured on Thursday when a blast ripped through a truck carrying troops and ammunition in the Swat area of Pakistan's North West Frontier Province.

The explosion, which occurred near the police lines at Mingora in Swat, was described by the Army as 'accidental.'

Local residents, however, claimed that there was an exchange of fire between troops and militants in the area, Dawn News channel reported.

There were some 30 security personnel in the truck, the report said, adding at least 16 soldiers were killed and eight others injured.

The blast came a day after thousands of troops were deployed in the Swat valley to counter the activities of pro-Taliban cleric Maulana Fazlullah and his Shaheen Commando Force.

NWFP Home Secretary Badshah Gul Wazir said the troops were deployed to reassert the writ of the local administration in about 59 villages where Fazlullah's armed men are running a parallel government.