The death toll from monsoon-related accidents reached 800 and two million people have been displaced by flooding following heavy rains across India, officials said on Sunday.

Indian commuters make their way through a waterlogged street after a heavy downpour flooded parts of Amritsar on August 12, 2008. Heavy downpours of rain continue to cross northern India as the south-west monsoon travels across the Indian sub-continent.

At least 26 people died in overnight accidents in northern Uttar Pradesh, taking the toll to 686 in the country's most populous state since the monsoon struck in June, Relief Commissioner G. K. Tandon said.

"Several districts are receiving continuous rains for the past month and a half," Tandon said in the state capital Lucknow as local aid agencies backed by World Health Organisation staff rushed emergency supplies to those affected.

Tandon put the number of people hit by the floods at 1.29 million and said 3,000 villages were swamped in Uttar Pradesh, in monsoon damage he described as "unprecedented".

Lightning strikes, boat accidents and house collapses are common during the June-September monsoon in tropical India.

In the adjacent eastern state of Bihar, 24 people died in rain-linked accidents since Saturday, a government spokesman said in the regional capital Patna.

The latest fatalities raised Bihar's monsoon death toll to at least 60 so far this month, according to the latest figures.

"Nearly 750,000 people are reeling under the impact of the floods," a Bihar Disaster Management Department spokesman said.

The army deployed rescue helicopters as experts warned seven rivers in Bihar were in spate and that more rain was forecast.

Northern Punjab saw 14 deaths in August, while 40 others died in heavy downpours in southern India during the month, according to separate official reports.

Authorities in New Delhi evacuated scores of farmers from the banks of Yamuna as the river flowed at danger levels, officials said on Sunday.

"The river banks are now swamped and we are ready to plug any breach that may occur in the anti-flood embankments," a city flood official said.

Last year more than 2,000 people were killed in the worst monsoon floods in decades that wreaked havoc across South Asia.