Authorities have raised to 5,500 the estimated number of people who perished in devastating floods that swept the northern Indian state of Uttarakhand last month.

At least 1,000 residents, Hindu pilgrims and tourists have been confirmed killed by the surging waters caused by heavier than normal monsoon rains that washed away homes, hotels, highways and cars.

"The total number of people still missing is 4,500," Chief Minister Vijay Bahuguna told a news conference in mountainous Uttarakhand state capital Dehradun on Monday.

Late last month authorities estimated the number of people missing in the Himalayan state to be 3,000.

"We will wait until July 15 and after that they (the missing) will be presumed dead and the process of compensation will start," Bahuguna added.

The government has promised to pay 500,000 rupees ($8,196) to families of each of those killed in the June 15 floods, which triggered widespread landslides.

Officials say some people initially reported missing may have returned home or continued with their travels, failing to notify authorities that they were safe.

Rescue workers have recovered bodies from rivers hundreds of kilometres (miles) downstream from the flood zone, underscoring the difficulties in finding all those killed in the floods.

A state lawmaker last month warned the death toll could exceed 10,000 in Uttarakhand, which is popular among Hindu devotees who throng local shrines during the June-September pilgrimage period.

Uttarakhand Chief Secretary Subhash Kumar said a 75-member rescue team was marooned in Kedarnath Valley after reaching the hilly region on July 3 and that the rescuers were running out of food.

"They are now rationing the food they carried for themselves," Kumar told reporters.

He added that 60 of the rescuers were sick from drinking contaminated water in corpse-littered Kedarnath, a popular Hindu pilgrimage site.

He said relief supplies have been sent to 250 villages that are still cut off in Uttarakhand and added that state workers stocked up stores in 92 remote hamlets with supplies for residents.

Thousands of Indian soldiers, backed by military helicopters, have been winding down massive rescue efforts.

More than 100,000 people stranded in the state have been evacuated.