Thousands of people have fled a major city in central Pakistan as authorities warn that swollen rivers could soon submerge the area, making them victims of the worst natural disaster in the nation's history.
In Punjab province, the normally bustling city of Muzaffargarh looked largely deserted on Tuesday after large numbers of people left following flood warnings the previous evening. Many men, however, stayed behind to guard homes and businesses.
The local government hospital had staffing shortages because many doctors and other workers had decided to leave.
The population of Muzaffargarh is around 250,000, said Hassan Iqbal, a senior government official in Dera Ghazi Khan district. The evacuation warning was issued only after authorities assessed that the floods could hit the city, Iqbal said.
The evacuation came as President Asif Ali Zardari returned on Tuesday to flood-ravaged Pakistan, where he faced a storm of criticism for visiting Europe as his country was gripped by its worst natural disaster.
The United Nations, relying on Pakistani figures, says the number of people affected by flooding over the past two weeks is 13.8 million - more than the combined total of the 2004 Indian Ocean tsunami, the 2005 Kashmir earthquake and the 2010 Haiti earthquake, although the death toll in each of those disasters was much higher than the 1,500 people killed in the floods.
Speaking from Islamabad, Martin Mogwanja, the UN's Humanitarian coordinator for Pakistan, said that "the disaster in many ways is as big as the disaster that Pakistan faced successfully after the 2005 earthquake when an estimated 3.5 million people were in need of assistance".
The UN special representative for the flood disaster, Jean-Maurice Ripert, estimated that "hundreds of millions of dollars will be needed to address the urgent humanitarian needs, and billions of dollars will be required for the rehabilitation and the reconstruction of infrastructure and livelihoods".
The widespread crisis has overwhelmed the government and frustrated citizens who have complained about slow or non-existent aid efforts.
A person is considered affected by the floods if he or she will need some form of assistance to recover, either short-term humanitarian aid or longer-term reconstruction help, the UN said.
Pakistani Prime Minister Yousuf Raza Gilani has called the crisis the worst natural disaster in Pakistan's history and appealed for international help.
The US and other countries have already donated millions worth of aid, and the American military has dispatched six helicopters from Afghanistan to assist in aid delivery and evacuations.
The hardest hit region has been the northwest, which also is the epicentre of Pakistan's fight against al-Qaeda and the Taliban.
But as swollen rivers have flown south and east, Sindh and Punjab provinces have also been affected.
In the Sindh province city of Sukkur, some flood victims could be seen camping on the edge of a highway.
Some villages near Sukkur were completely submerged and residents had to swim in the floodwaters to transfer their remaining belongings.
Rescue work has been hampered by ongoing monsoon rains, which have washed away roads and bridges and made it impossible for helicopters to fly at certain times.
The floods hit the country at a time when the government is already struggling with a faltering economy and a brutal war against Taliban militants that has killed thousands of people.
The patchy government response has given room for Islamist groups, some allegedly linked to militant outfits, to step in and offer their own aid to displaced and hungry flood victims.
APTN