Pakistan soldiers moved to try to encircle Taliban and al Qaeda militants in the South Waziristan mountains near the Afghan border, in a high-stakes offensive aimed at crushing the insurgency in its toughest stronghold.

Military reports Sunday indicated soldiers, whose offensive began before dawn Saturday, were making advances amid stout resistance. Some 30,000 Pakistani soldiers were moving into the area from three directions to face as many as 10,000 Pakistani and foreign militants, many of them veterans of battles in Pakistan and Afghanistan.

Hundreds of thousands of civilians were said to be fleeing South Waziristan to neighboring areas. "There is a full-fledged war-like situation here, and we are packing to flee however we can find a way, but there is no safe passage," said Muhammad Nawaz, 29 years old, in a telephone interview from the Taliban-controlled town of Makeen. The area is closed to reporters.

The army has failed in previous attempts to reassert its control over the area. Instead, the government made peace deals with the Taliban faction that controls the region. But officials say a wave of terror attacks that left more than 160 people dead in the past two weeks has stiffened their resolve, and there will be no deals in South Waziristan this time.

Battles and skirmishes were reported around a handful of towns Sunday. "I heard intense shelling with artillery pounding the mountain behind our village. I saw the big trees in the forest caught fire and flames were rising high," said Muhammad Alam Mehsud, 47, who fled with his 12-member family during a lull in the fighting.