U.N Secretary-General Ban Ki-moon traveled to flood-ravaged Pakistan on Sunday where he urged international donors to step up aid for millions of victims of the country's worst humanitarian disaster. The U.N chief met both Prime Minister Yousuf Raza Gilani and President Asif Aliz Zardari to discuss relief efforts.

Pakistani leaders say that the devastating floods, triggered by torrential monsoon rains, have disrupted lives of up to 20-million people across the country. The floodwaters have inundated thousands of villages and towns, washed away roads key bridges, crops, and livestock.

The United Nations has appealed for $459-million to deal with the immediate aftermath of the floods, saying billions of dollars will be needed in the long term to restore victims and their livelihoods. But U.N officials say foreign aid has been slow in coming and only a quarter of its initial appeal has arrived so far.

U.N Secretary-General Ban Ki-moon says his visit to Pakistan's flood-hit areas was meant to share his sympathy and solidarity of the United Nations with both the government and the Pakistani people.Ayaz Gul gives more details from Islamabad.

"I am here also to urge the world community to speed up their assistance to Pakistan people," Mr. Ban said.

He told reporters he would report back to the U.N General Assembly meeting set for Thursday to discuss Pakistans needs and the assistance required.

"We will try to mobilize all necessary assistance. And remember that the whole world is behind the people of Pakistan in this time of trial," Mr. Ban said.

U.N agencies and aid groups say that at least six million flood victims are now dependent on humanitarian assistance to survive and Pakistan needs increased international assistance to deal with the crisis. Pakistani officials have put the death toll in flood-related incidents at around 1,600.

But U.N officials have warned of a second wave of death from disease among the sick and hungry victims if help does not arrive in time. They have already confirmed cases of water-borne diseases in the disaster zone.

The United States has already provided more than $76-million in relief aid and has sent helicopters to help in Pakistani relief efforts.