Concerns are mounting that the assault in South Waziristan, which presents the military with its biggest challenge yet in the war against militants, will spark another refugee crisis ahead of heavy snow in a bitterly cold winter.
US officials flew in to consult Pakistans civilian and military leaders as warplanes pounded enemy hideouts and ground troops advanced closer towards diehard Taliban bastions for a third consecutive day.
People who fled to neighbouring district Dera Ismail Khan, on foot and stuffed into pick-up trucks weighed down with bedding and chickens, spoke of intensifying fighting and air strikes targeting villages.
'I decided to leave when my neighbours house was destroyed by jet fighters,' said Rahim Dad Mehsud, a labourer from Tiarza who said he walked three days to leave South Waziristan with 12 relatives.
Mehsud, who comes from the same tribe as Pakistani Taliban leader Hakimullah Mehsud and whose members are a leading faction in the Tehreek-i-Taliban Pakistan (TTP) movement, said ordinary civilians were the victims of a pointless operation.
'The Taliban cannot be eliminated through a military operation. Both are killing us,' he added. Some displaced accused the authorities of maltreating those from the tribal belt, which has a fierce tradition of independence.
'Everyone here -- police and security forces -- treat us with suspicion and contempt, as if we are terrorists,' said 16-year-old Fayyaz-ud-Din, queuing up at a registration centre in a cricket stadium.
UN and Pakistani officials say that since August more than 100,000 people have fled South Waziristan, part of the tribal belt on the Afghan border that the United States calls the most dangerous place on earth.
Prime Minister Yousuf Raza Gilani urged the international community to provide financial assistance for relief and reconstruction at talks with top US General David Petraeus on Monday, his office said.
The US has recently praised Pakistan for taking military action against Taliban and Al-Qaeda-linked militants, following a prolonged assault in the northwest Swat valley -- considered a less difficult fight than Waziristan.
US officials say Al-Qaeda fled into Pakistans tribal areas after US-led operations toppled the Taliban in Afghanistan in 2001 and now use the area as a base for plotting attacks on the West.
Pakistan says its offensive is concentrated against the TTP, whose estimated 10,000 to 12,000 fighters are spread across about half of South Waziristan.
Around 20,000 to 25,000 troops are involved in the three-pronged push, a much-anticipated assault seeking to crush networks blamed for some of the worst attacks that have killed more than 2,250 people in the last two years.
Taliban fighters have mounted fierce resistance, dragging troops into ground fighting with six soldiers killed so far. The military said 60 militants were killed in the first 24 hours.
It is impossible to corroborate information from within South Waziristan.
The military has sealed off exit and entry points, imposed curfews and jammed phone lines even into neighbouring districts Tank and Dera Ismail Khan.
Shah Barat, a labourer from Ladha, a Taliban stronghold in South Waziristan, told AFP he and 11 relatives took two days to reach Dera Ismail Khan on Saturday, the day the operation began.
He said clashes between security forces had intensified and several houses were destroyed in air strikes, killing mostly women and children.
'Mostly innocent tribesmen, women and children are being killed. The Taliban have their hideouts in the mountains, but mostly houses have been hit in jet strikes,' Barat said in Dera Ismail Khan.
Barat said he had rented a small house in Dera Ismail Khan for 6,000 rupees (73 dollars) per month, which was a huge burden on his meagre income.
'We have nothing to do with the military operation. We want peace and it is the third time I had to abandon my home due to fighting,' he added.
Numerous previous offensives against militants in the tribal belt have had limited success, costing the lives of 2,000 troops and ending generally with peace agreements that critics say simply gave the enemy a chance to re-arm. -AFP