The U.N. Office for the Coordination of Humanitarian Affairs said in a release issued in New York the monsoon rains also have inundated thousands of acres of standing crops and damaged many houses and infrastructure.
OCHA representative Jens Laerke told reporters in Geneva, Switzerland, the rains are expected through the month.
"Pakistani authorities continue rescue and relief activities in affected areas, particularly Balochistan, Khyber Pakhtunkhwa, Punjab and Sindh provinces," Laerke said. "They have not requested international assistance at this stage. OCHA and humanitarian partners are closely monitoring the situation and stand ready to assist if required."
The U.N. World Health Organization will provide emergency health and diarrheal disease kits, water purification tablets and malaria medicine for 5,000 people. Other humanitarian agencies also have offered their support and stand ready to assist, the U.N. release said.
The United Nations said flash flooding also had hit neighboring Afghanistan, with at least 13 villages in Kabul province affected and dozens of people reportedly killed.