Major General Athar Abbas, Pakistan Military Spokesman, said, "Their (militants) response in the operation area where we are going is limited against the security forces as the security forces are very well prepared and well equipped."

About 28,000 soldiers are battling an estimated 10,000 hard-core Taliban, including about 1,000 tough Uzbek militants and some Arab al-Qaeda members.

The army says it has surrounded the militants in their main zone and soldiers were attacking from the north, southwest and southeast.

But the militants have had years to prepare their bunkers in the land of arid mountains and sparse forests.

More than 100,000 civilians have fled from South Waziristan in anticipation of the offensive. About 20,000 have come out in the last few days. An army officer said up to 200,000 people could flee.