The death toll in floods rose to 837 Saturday as rescue workers tried to reach tens of thousands of people stranded in north-western Pakistan, officials said.

Rivers bloated by monsoon rains submerged thousands of villages, washed away dozens of bridges and telecommunication installations, blocked roads and inundated millions of acres agricultural land.

Iftikhar Hussain, the provincial Information Minister, said in the regional capital Peshawar that more than 800 deaths had been confirmed.

The Provincial Development Management Authority reported more than 100 people missing in Khyber-Pakhtunkhwa, the worst-hit area with more than 400,000 people displaced.

Hundreds of soldiers were dispatched to rescue and relief in Khyber-Pakhtunkhwa's worst flooding since 1982.

Soldiers had moved 14,250 people to safety, including 2,800 tourists stranded in mountain resort of Kalam, the military said.

'Seventeen army helicopters are taking parts in these relief activities besides motor boats,' it said.

Hussain appealed to the international community to provide immediate help to prevent 'a major humanitarian disaster'.

The UN Office for the Coordination of Humanitarian Affairs and other UN organisations pledged support for the victims Friday.

US Ambassador Ann Patterson also promised seven helicopters to assist the relief efforts.

Flooding in the Pakistan-administered Kashmir region claimed 24 lives. Thirteen more people died in the central province of Punjab where large areas were flooded.

Pakistan experiences an annual monsoon, which brings heavy rains to the whole subcontinent in July and early August.

Dozens of people were killed last week and tens of thousands displaced in floods in the south-western province of Balochistan.

The national Meteorological Department has predicted 10 percent more rain this year than during a normal monsoon season.