Rescuers and residents resumed searching on Tuesday for survivors as the death toll from five days of torrential rain rose to almost 400, with authorities warning monsoon downpours would continue until the weekend.

Flash floods triggered by cloudbursts in the mountainous northwest have brought destruction since Friday in the worst spell of this year's monsoon.

At least 21 people have died in monsoon rain-related incidents in Pakistan, authorities said, pushing the nationwide death toll over the last week above 400 as floods and landslides continue to devastate large parts of the country.