More than 400 people have been killed and thousands are missing in Pakistan due to incessant rains and flash floods, officials said.

Balochistan and North West Frontier Province have been the worst hit by rains and snow-related incidents, officials said. In Balochistan, 300 people died after a check dam near Pasni town burst, they said.

"We have reports that over 1,000 are still missing. We fear that the death toll may rise to 500 or 600. But we do not have confirmed reports as yet," Sana Ullah Baloch, a senator of the Balochistan National Party said.

Assessing the casualties was difficult as the population is scattered over a large area, he said.

Two more small dams burst in the province resulting in a number of villages being washed away, reports from the area said on Sunday.

The Chalvi dam in Kolach Union Council in Pasni tehsil and the Gawar Bagh dam in Turbat district burst on Saturday afternoon due to persistent rains and flash floods, the local daily Dawn said.

Hundreds of people are reported missing in Suntesar, the last human settlement before the floodwater falls into the Arabian Sea near Gwadar, the paper quoted officials as saying.