Torrential rain was forecast to lash flood-hit Pakistan on Sunday, hampering the aid effort and threatening to deepen a crisis affecting 15 million people in the country's worst ever floods.
Helicopters were grounded in the northwest while rescuers rushed to evacuate families in the poor southern farming belt of Sindh, where officials were on red alert for a deluge that could burst the banks of the swollen Indus River.
Fresh downpours hammered the northwestern province of Khyber Pakhtunkhwa Saturday, with experts predicting at least two more days of rain, adding to the misery of the millions made homeless.
"The situation is bad, particularly in the Swat valley, and we have advised people in low-lying areas to vacate their homes as river water levels are rising," said Adnan Ahmed, a provincial official.
The UN special envoy dispatched to help with the flood relief effort cancelled a flight to stricken areas and Prime Minister Syed Yusuf Raza Gilani also postponed his trip for a day because of the rain.
At least 11 people were killed and 31 injured when a truck carrying flood evacuees fell into a ditch on Saturday after skidding off a slippery road in the northwestern district of Lower Dir, police officer Mumtaz Zareen said.
Those uprooted from their homes in Sindh have been moved to government buildings, schools and tents, but many families in low-lying areas resisted evacuation, said irrigation minister Jam Saifullah Dharejo.
"I didn't want to leave but when the water levels got high and we were hungry and couldn't cook anything... my brother told me we should leave," said Najma Bibi, 30, as she searched for food with her eight-year-old son.
Countries including Britain, China, Australia, France and the United States have pledged tens of millions of dollars in aid for victims of the nearly two-week-old disaster.
The United Nations estimates at least 1,600 people have been killed by the floods that have ravaged the largely impoverished, insurgency-hit country, sweeping away entire villages.
The flooding has threatened electricity generation plants, forcing units to shut down in a country already suffering a crippling energy crisis.
In Khyber Pakhtunkhwa, head of flood relief operations Major General Ghayoor Mehmood said some 1,400 people have been killed, with 213 still missing.