Pakistan has issued a flood alert for some southern districts, warning of torrential rains, as rescue teams continued searching for missing people in the northwest, where severe floods have killed hundreds over the past week.

Pakistan has received higher-than-normal monsoon rainfall this year, triggering floods and mudslides that have killed more than 540 people since June 26.

Rescuers were racing against time to find survivors after flash floods killed at least 337 people in Pakistan 's Khyber Pakhtunkhwa province. The northwestern province was struck by cloudbursts and torrential monsoon downpours on Friday, triggering flash floods and landslides in the mountainous Buner district.