Updated at 6:48 a.m. Eastern.
A shipload of U.S. Marines and helicopters arrived to boost relief efforts in flooded Pakistan, but the prime minister told The Associated Press his country needs more international help to cope with one of the worst natural disasters in its history.
The United Nations warned the crisis was far from over, saying dams in Sindh province could still burst in the coming days. More rain fell around the country Thursday, and monsoon season is forecast to last several weeks still.
CBS News' Farhan Bokhari reports that U.N. Secretary-General Ban Ki-moon is scheduled to arrive in Pakistan on Saturday to survey the crisis relief efforts. Sen. John Kerry, the chairman of the Senate Foreign Relations Committee, is due to arrive next Wednesday.
Spokesman Maurizio Giuliano said U.N. officials roughly estimated that up to one-fourth of the country is or had been affected by the floods, though those areas were not necessarily under water.
The government has been sharply criticized for a slow and patchy response to the floods, which has killed 1,500 people left and left an estimated 7 million people needing emergency assistance, their homes destroyed, damaged or inundated with muddy water and unlivable.
President Asif Ali Zardari - whose decision to go ahead with a trip to Europe when the disaster began was condemned by many - made his first visit to victims of the disaster on Thursday, according to state-run Pakistan Television that gave few details of the trip.
The United States has pledged $71 million in emergency assistance to the country, which is key in the fight against al Qaeda and the Taliban as well as stabilizing neighboring Afghanistan. It has also deployed the military to help, as it often does after major disasters.
The USS Peleliu arrived off the coast near Karachi on Thursday along with 19 helicopters and about 1,000 Marines.
The helicopters set off immediately for flood-hit areas to rescue stranded people and deliver food and other supplies.
An Associated Press reporter flew with Prime Minister Yousuf Raza Gilani over parts of Punjab, Sindh and Baluchistan provinces. Seen from the air, the extent of the disaster was clear, with the aircraft often flying for many minutes over a mostly flooded landscape.
"All I say is that we need more help from our international friends," he said. "We need more such helicopters because the magnitude of the destruction was far more" than earlier government assessments.
"I also urge my own countrymen and women to help their brothers and sisters," he said.
Flood survivors already short on food and waterof Ramadan, a normally festive, social time marked this year by misery and fears of an uncertain future.
While millions of flood-affected people were performing the fast, Mufti Muneebur Rehman, one of the country's top religious scholars, said victims living in difficult conditions dependent on charity could skip the fast and perform it later in the year.
"I cannot disobey God, so I am fasting as it is part of my faith no matter what the conditions are," said Fazal Rabi, 47, who was staying in a tent village in Akbarpura in the northwest, where many people are especially devout.