Pakistan has asked Washington for "ownership" of US drones carrying out attacks on its territory, President Asif Ali Zardari said Wednesday.

"Democracy doesn't believe in half measures. We've asked for the ownership of the drones," he said, when asked about reports that the US has agreed to pass control of drone aircraft to Islamabad.

Speaking in London after talks with British Prime Minister Gordon Brown, Zardari said Islamabad was "negotiating terms" with the US over the drones, which have long been a source of tension between Washington and Islamabad.

Last month Pakistani Foreign Minister Shah Mehmood Qureshi said that US drone attacks are working to the advantage of the extremists, citing "red lines" in Pakistan's cooperation with the United States.

Pakistan is deeply opposed to the drone attacks, around 37 of which have killed over 360 people since August 2008, saying they violate its territorial sovereignty and deepen resentment in the nuclear-armed nation.

Zardari had discussions with President Barack Obama in Washington last week.

In other comments, Zardari said the fight against Taliban militants in Pakistan's tribal areas which border Afghanistan would be a long-term struggle -- and underlined the importance of defeating them.

"If I were to say that they are trying to create a new world order, I would not be wrong," he said, adding that the fight against militants "is not a short-term affair. It is a long-term endeavour."

Zardari dismissed suggestions that Pakistan's nuclear arsenal was vulnerable in the face of the Taliban offensive.

"You can ask anybody who is responsible in any government and they will tell you that they are not concerned," he said.

"They assure their governments that they are quite satisfied with the security situation in Pakistan and with the command and control system that Pakistan already has."

Brown announced Britain would provide 12 million pounds (13.4 million euros, 18.2 million dollars) in immediate humanitarian aid to help ease the plight of civilians caught up in the fighting in Pakistan's Swat Valley.

"Let there be no mistake, Pakistan is already taking action against terrorism. President Zardari's troops are risking their lives fighting extremists," Brown said.

"We will help provide shelter, water, food, and sanitation for those people who have been displaced by these terrorist acts."

The UN refugee agency said Wednesday that more than 670,000 people had fled fighting in the northwest over the last 11 days, with an additional 170,000 people streaming out of the area in the space of 24 hours.

Terrified residents trapped in Mingora, the main town in the region, told AFP that militants had planted mines and were digging trenches.

A shopkeeper, who did not want to give his name, said people were "becoming mentally ill" in the face of the militants' campaign and he called on the government "to pull us out of here."

Zardari threw doubt on a claim by the BBC's Urdu Service that his government controls less than 40 percent of the Northwest Frontier Province and neighbouring areas.

"I think that is an incorrect survey," he told journalists.