UN chief Ban Ki-moon on Sunday pledged to speed up international aid for as many as 20 million people hit by Pakistan's floods, warning that the country's worst humanitarian crisis was far from over.
The United Nations has appealed for 460 million dollars to deal with the immediate aftermath of the floods but has warned that billions will be required in the long term with villages, businesses, crops and infrastructure wiped out.
Pakistan's weak civilian government has appealed to the international community to help it cope with the challenges of a crisis that Prime Minister Yousuf Raza Gilani has compared to the 1947 partition of the sub-continent.
Ban held talks with Pakistani leaders and flew with President Asif Ali Zardari over some of the worst affected areas of central province Punjab.
"I'm here to urge the world to step up their generous support for Pakistan," Ban told a joint news conference, with Zardari saying he would never forget "heart wrenching" scenes of destruction he had witnessed.
Charities have complained that relief for those affected by the worst natural disaster in Pakistan's history was lagging far behind what was needed, with six to eight million dependent on humanitarian aid to survive.
The UN secretary general said a possible 20 million, or one in 10 Pakistanis were directly or indirectly affected by the disaster and that one fifth of the country was ravaged by floods.
"This disaster is far from over. The rains are still falling and could continue for weeks.
"The United Nations and international community and international humanitarian community are moving as fast as we can to help the government deliver desperately needed humanitarian assistance," he said.
Ban said he would report back to the UN General Assembly on Thursday and discussions would continue on how to provide funds beyond the 460 million earmarked for an initial 90 days.
Scuffles broke out near the southern city of Sukkur on Sunday, when dozens of flood survivors angrily protested against the authorities over a lack of food and facilities as they struggle to survive, police and witnesses said.
Aid agencies were monitoring the risk of "a second wave" of deaths induced by the floods in the shape of water-borne diseases.
The United Nations has confirmed at least one cholera case and said 36,000 people were reportedly suffering from acute diarrhoea.
Ban announced a further 10 million dollars from the UN central emergency response fund, making a total of 27 million dollars since the beginning of the crisis and said "as the waters recede, we must move quickly".
The UN estimates that 1,600 have died in the floods. The government in Islamabad has confirmed 1,384 deaths and said that 20 million people have been hit by the disaster.
Some of the worst-hit areas are in the volatile northwest, where Taliban militants have been locked in fighting with Pakistani troops, and the wealthiest and agriculturally most important areas of Punjab and Sindh.
Fresh foods hit the southwestern province of Baluchistan overnight, devastating hundreds of villages and causing tens of thousands to flee, said Sher Khan Bazai, the commissioner in the town of Jaffarabad.
"The situation is grim. I saw people sheltering on the roofs of trucks and buses as bridges and roads have been washed away," Bazai said, adding that authorities had only one helicopter and four boats for rescue missions.
The nuclear-armed country of 167 million is on the front line of the US-led fight against Al-Qaeda and Western governments have traced overseas terror plots back to Taliban and Al-Qaeda camps in the lawless tribal mountains.
The United States has increased to seven the number of military helicopters in Pakistan to assist with the relief efforts but weather has severely restricted their ability to fly.
US Defense Secretary Robert Gates has promised 19 helicopters for the aid effort, which should be on the ground in coming days, the embassy said.