In northern Sindh, local authorities issued a new evacuation order for Shahdadkot, a town of about 300,000, for the remaining few tens of thousands of people to leave as floodwaters approached the town.
Shahdadkot is certainly in danger, said relief commissioner for Sindh Riaz Ahmed Soomro. People have been asked to evacuate, but it's a very big town. People had built an artificial embankment but the pressure is increasing.
Downstream in Thatta, the towns of Sujawal, Daro and Mirpur Batoro, with a combined population of 400,000, were ordered evacuated after the swollen Indus river broke through an embankment early Thursday morning.
Many residents of the Indus delta area, about 100 km (62 miles) east of Karachi, had already left, but thousands remained, said Saleh Farooqi, director general of the National Disaster Management Agency's Sindh office. If a second levee breaks, more towns could be inundated.
Floodwaters are beginning to recede across the country, but because of high tides in the Arabian Sea and the possibility of more rain, the risk of flooding remains in Sindh.
The spokesman for the powerful Pakistani Army said difficulty in reaching certain areas, where 800,000 people are accessible only by air, could fuel social unrest.
If the aid doesn't reach certain areas, then yes, the people will become restive, said Major General Athar Abbas.
The worst floods in decades have made the government more unpopular, heightening concerns about a nation that is already battling Islamist militants.
In Sukkur, to the north, flood victims crowded relief camps and said incidents of disease were increasing.
The children are getting sick, a man who called himself Bangul told Reuters. I myself am not feeling well.
He said some people had started returning to their villages, even though many were still flooded. We can only see the roof and minaret of the mosque, he said. We think maybe it will take six months to dry up and then we can go back.
POSSIBLE TALIBAN THREAT
Pakistan's government, and its ally the United States, have warned that the Islamist militants the military is battling may try and exploit the chaos. Washington sees Pakistan as a frontline state in its war against the Taliban and al Qaeda.
An unnamed official in Washington, quoted by the BBC, warned that the Pakistani Taliban might target foreign aid workers, although aid groups in Pakistan brushed off concerns.
One government official said he did not think the Taliban would attack as this would trigger a public backlash, while army spokesman Abbas said he had not received reports of any threat to aid workers.
The local people are all out to welcome them (aid workers), he said. In this distressed situation, anyone is welcome.
Azam Tariq, a spokesman for the Tehrik-e-Taliban Pakistan (Taliban Movement of Pakistan), told Reuters: We will not tolerate American aid. They want to use it for their own interest and don't want to help the people of Pakistan. They have their own nefarious designs.
In Washington, Pakistan's finance minister and central bank governor joined International Monetary Fund talks on salvaging the economy.
The talks are ongoing at a technical level and are focussed on getting a better sense of the impact of the floods on the economy, IMF spokesman Gerry Rice told reporters.
The talks, which began on Monday, are still in the early stages and should last until late next week.
Rice said the sides would explore all options to stabilise the economy, including easing targets on Pakistan's existing $11 billion (7 billion pounds) IMF loan and tapping IMF resources from an emergency fund for countries hit by natural disasters.
He urged donors to give grants, not loans, for rebuilding projects to avoid adding to Pakistan's debt burden. The Pakistan delegation is scheduled to meet World Bank President Robert Zoellick on Wednesday, a World Bank spokesman said.
The floods have damaged at least 3.2 million hectares (7.9 million acres) -- about 14 percent of Pakistan's entire cultivated land -- according to the United Nation's food agency. The total cost so far in crop damages is about 245 billion rupees ($2.86 billion).
According to the United Nation's Office for the Coordination of Humanitarian Affairs, 60 percent, or $274.7 million out of $459.7 million, of funding for emergency response has been met.
(Reporting by Augustine Anthony, Kamran Haider, Zeeshan Haider and Rebecca Conway in Islamabad, Faisal Aziz and Sahar Ahmed in Karachi, and Robert Birsel in Sukkur; Writing by Chris Allbritton; Editing by Sanjeev Miglani and Eric Beech)
(For more Reuters coverage of Pakistan, see: http://www.reuters.com/places/pakistan)