About 30,000 troops have joined the relief effort, with large parts of the north-west submerged by the worst monsoon rains in memory.

There are also fears that with more rain forecast for the next 24 hours, some areas face further threats.

Part of the main north-south motorway into the region was reopened on August 1, before reportedly closing again.

The opening allowed some aid supplies into the flooded area while permitting some people to flee the region.

A spokesman for the disaster management authority of Khyber-Pakhtoonkhwa province - formerly known as North West Frontier Province - said an aerial survey was being conducted to determine the full extent of the flooding.

"It has shown that whole villages have been washed away, animals have drowned and grain storages have been washed away," said the spokesman, Latifur Rehman.

"The destruction is massive."