Pakistani President Asif Ali Zardari and a senior US senator warned on Thursday that Taliban insurgents were trying to exploit rising anger over the country's worst floods to promote their cause.

More than 4 million Pakistanis have been made homeless by nearly three weeks of floods, the United Nations said on Thursday, making the critical task of securing greater amounts of aid more urgent.

Eight million people are in urgent need of humanitarian assistance and many may not care where they get it. The floods began washing away villages and destroying roads and bridges just after the government had made progress in stabilizing the country through offensives against the Taliban.   

Islamist charities, some with suspected links to militant groups, stepped in to help victims, possibly boosting their image at the expense of the US-backed government, which is still accused of being lax nearly three weeks into the crisis.

The United States led a stream of pledges of more funds for Pakistan during a special meeting of the UN General Assembly. US Secretary of State Hillary Clinton promised a further $60 million, bringing to more than $150 million the contribution the United States would be making toward emergency flood relief.

British Development Secretary Andrew Mitchell said London was doubling its contribution to nearly $100 million. Speaking for the European Union, Belgian Foreign Minister Steven Vanackere promised a further 30 million euros ($38.5 million) on top of 110 million euros already committed.   

The United Nations has issued an appeal for $459 million, of which Secretary-General Ban Ki-moon said about 60 percent had been pledged.

"Make no mistake: this is a global disaster, a global challenge," Ban said calling the crisis in Pakistan "one of the greatest tests of global solidarity in our times."    

US Senator John Kerry, who visited flood-hit areas with Zardari, said action must be taken to prevent anyone from exploiting frustrations. "We need to address that rapidly to avoid their (Pakistani's) impatience boiling over, and people exploiting that impatience and I think it's important for all of us to understand that challenge," Kerry said, in a clear reference to the Taliban. "We also share security concerns."    

About one-third of Pakistan has been hit by the floods, with waters stretching tens of miles (km) from rivers. In a small town in Punjab, people waved empty pots and pans at a military helicopter, wondering, like millions of others, when food supplies will arrive.

Aid agencies have been pushing for more funding as they try to tackle major problems such as food supplies, lack of clean water and shelter and outbreaks of disease.   

The United States needs a stable Pakistan, which it sees as the most important ally in the war against militancy, especially in neighboring Afghanistan, where a Taliban insurgency is raging.

In a sign of growing concerns over the ramifications of the floods, Kerry said $200 million from the $7.5 billion US aid package for Pakistan over five years, which he co-authored, would be diverted to the relief effort.   

The bill was unpopular in Pakistan as it ties some funds to fighting militancy, to cooperation in stopping nuclear proliferation and ensuring Pakistani civilian government dominance over the military.

Kerry said he was shocked after seeing miles of destroyed homes and displaced people in camps in sweltering heat. Floods have ruined crops over more than 1.6 million acres (647,500 hectares), hammering the mainstay agriculture industry. Aid workers say water could stagnate on the surface for months, making planting difficult. - Reuters