Pakistani troops killed 33 militants but faced mortar fire and street battles as they pressed an offensive against Taliban and foreign extremists on Saturday, the military said.

No information provided by the army can be verified because communication lines are down and journalists and aid workers are barred from access to the area on the wild Afghan border.

The latest casualties reported in a military statement bring to 297 the total number of insurgents reported killed since the operation was launched in the mountainous tribal terrain of South Waziristan on October 17.

Seventeen militants were killed and two soldiers injured when government troops surrounded the town of Karama, a stronghold and training centre of Uzbek militants, the military said.

Fighting in streets is going on and house to house search is in progress. Terrorists have converted the houses into strong bunkers and are holding towers in strength and with snipers.

military statement

"Fierce fighting is going on between security forces and foreign terrorists present in the area," it said.

In nearby Kanigurram, troops were facing stiff resistance, including mortar fire, the statement added.

"Fighting in streets is going on and house to house search is in progress. Terrorists have converted the houses into strong bunkers and are holding towers in strength and with snipers," it said.

Three militants died during exchanges of fire there, and another 13 were killed when troops closed on the "terrorists' stronghold" of Sararogha, the military said.

Around 30,000 troops are taking part in the offensive against an estimated 10,000-12,000 militants in the semi-autonomous and lawless tribal belt. Relief workers say more than 200,000 people have been displaced by the fighting.

Numerous previous offensives in the tribal belt have had limited success, costing the lives of 2,000 troops and ending generally with peace agreements that critics say gave the insurgents a chance to re-arm.