The number of people displaced by fighting in Pakistan's turbulent northwest has doubled to one million in recent days, the United Nations' refugee agency said Friday.

Children from Swat arrive on a truck at a refugee camp in Mardan, northwest Pakistan, on Thursday. ((Greg Baker/Associated Press))

Up to 200,000 people have arrived in safe areas in the past few days and another 300,000 are on the move or are about to flee, Ron Redmond, spokesman for the UN High Commissioner for Refugees, said Friday. The new numbers are in addition to the estimated 555,000 people displaced from the area since August, he told reporters in Geneva.

There has been renewed violence in the northwest in the past few days after the Taliban took control of large areas of the Swat valley in the northwest. Particularly contentious was a militant foray in late April into the Buner region, about 100 kilometres from Pakistan's capital, Islamabad.

The Pakistani government, under increasing international pressure to crack down on militants and alarmed by the Taliban's new proximity to the capital, began an army offensive into the Swat last week.

The military campaign has effectively nullified a peace pact under which the government allowed the implementation of Islamic law in Swat and the surrounding region.

The Swat valley, once an alpine resort popular with tourists, was violently seized by the Taliban in 2007. The government has sent the army into Swat three times in the last year and a half to fight the Taliban, and has managed to temporarily subdue the militants on each occasion.

"Nobody really doubts the army has the power to push back the Taliban," said freelance reporter Graham Usher, reporting from Islamabad. The problem, he said, is whether there is "an effective civil administration and functioning police force that can then step in and govern the territory once the army leaves.

Taliban keep returning

"In the last 18 months every time the army has stepped back, the Taliban have re-entered and re-conquered the city. And that is the fear, [that] this will happen again this time," he told CBC News.

On Friday, Pakistan continued its assault on the area, sending fighter jets to bomb Taliban targets in and around Mingora, the main town in the Swat valley.

The Pakistani government is expected to begin a "major operation" within the next two days to take Mingora, Usher said.

While many residents have fled the city, tens of thousand remain. Some have said the Taliban are not allowing them to leave, perhaps because they want to use them as "human shields" and make the army unwilling to use force.

"We want to leave the city, but we cannot go out because of the fighting," said one resident, Hidayat Ullah. "We will be killed, our children will be killed, our women will be killed and these Taliban will escape."

"Kill terrorists, but don't harm us," he pleaded.

Thousands crowd makeshift camps

There are about 11 functioning refugee camps in West Pakistan to receive the displaced, said Usher.

"Tens of thousands of people are living in makeshift camps or staying with relatives, and the Pakistani government has called on the international community to donate money, resources and tents," he said.

"But at the moment it has to be said the Pakistani government is ill-prepared for the refugee exodus we're expect the from Swat, especially if the numbers are something like 1 million which is what the UN, [and] the International Red Cross are predicting."

The International Committee of the Red Cross said Thursday it no longer had access to the Swat region and could no longer verify casualty reports.

"Clearly, we're facing a major humanitarian crisis," said Red Cross spokesman Sebastian Brack, adding his organization is mobilizing trucks, medical and supplies and food.

The Swat Taliban are estimated to have up to 7,000 fighters — many with training and battle experience — equipped with rocket-propelled grenades, explosives and automatic weapons. They are up against some 15,000 Pakistani troops who until recent days had been confined to their barracks under the peace deal.