Pakistani flood survivors already short of food and water have begun the fasting month of Ramadan, a normally festive, social time marked this year by misery and fears of an uncertain future.
A US Navy ship carrying helicopters and 1,000 Marines reached Pakistan's southern coast to boost relief efforts, as the United Nations warned the disaster was far from over, saying dams in Sindh province could still burst in the coming days.
"There is more water coming along," said spokesman Maurizio Giuliano.
He said the UN estimated up to a quarter of the country is or had been affected by the worst floods in a generation, though that did not necessarily mean the areas were under water.
President Asif Ali Zardari, who has been sharply criticised for visiting Europe as the floods began, made his first visit to victims of the disaster on Thursday and toured one of the dams.
The floods, triggered by monsoon rains, hit the country's North West more than two weeks ago and spread down the country, inundating thousands of villages. About 1,500 people have died so far, and the UN estimates up to seven million people need emergency assistance.
Damage to crops, roads and bridges has caused food prices to triple in some parts of the country, adding to the pain of those marking the fasting month.
"Ramadan or no Ramadan, we are already dying of hunger," said Mai Hakeema, 50, who sat alongside her ailing husband in a tent outside the city of Sukkur. "We are fasting forcibly, and mourning our losses."
Observant Muslims fast from dawn to dusk each day for a month each year to control their desires and show empathy for the poor. The month is marked by increased attendance at mosques, a rise in charitable giving and family gatherings that coincide with the evening breaking of the fast.
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 miss the fast and perform it later in the year.