Pakistan has ordered fresh evacuations from southern Sindh Province.
The towns of Sujawal, Daro, and Mirpur Batoro, with a combined estimated population of 400,000, were ordered evacuated after the swollen Indus River burst through an embankment.
Saleh Farooqi, director-general of the National Disaster Management Agency's Sindh office, said that many residents of the Indus delta area, about 100 kilometers east of Karachi, had already left, but "thousands" remained.
The floods, triggered by heavy monsoon rains a month ago, have affected more than 17.2 million people, including some 3.8 million in Sindh, and killed more than 1,500.
Meanwhile the United Nations says it is reviewing security measures for its aid workers in the country after a warning of new threats from the Pakistani Taliban.
The militant group said it "plans to conduct attacks against foreigners participating in the ongoing flood relief operations in Pakistan."
compiled from agency reports