The Pakistani navy is co-ordinating a major operation to rescue survivors from a devastating disaster that has killed 1,600 people and left 2m homeless.
However, more heavy rain is hampering rescue efforts where up to 15m people are believed to have been affected by the country's worst flooding for 80 years.
Rubber and wooden navy boats set out from areas in Sindh province, where flood waters burst from the Indus River across vast distances, to help Pakistanis who have watched safe ground shrink by the hour and waters swallow up their livestock.
Helicopters were grounded in the northwest while rescuers rushed to the poor southern farming region of Sindh.
Floodwaters have moved down from the northwest to the agricultural heartland of Punjab and on to southern Sindh along a trail more than 1,000km long.
New downpours have hit the northwest province of Khyber Pakhtunkhwa, with forecasts for more rain adding to the misery of the millions made homeless by the floods.
'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.
At least 11 people were killed and 31 injured when a truck carrying flood evacuees fell into a ditch yesterday after skidding off a slippery road in the northwest district of Lower Dir.
With the floods sweeping south, those uprooted from their homes in Sindh province have been moved to government buildings, schools and tents.
The Indus river is at very high flood levels and water breached a canal in Tori Band village, forcing people to flee with their families on donkey and horse carts with whatever possessions they could grab.
Countries including Britain, China, Australia, France and the US have pledged tens of millions of euro in aid for victims of the disaster.
The UN estimates at least 1,600 people have been killed by the floods as entire villages have been swept away.
The flooding has threatened electricity generation plants, forcing units to shut down in a country already suffering a crippling energy crisis.
