More than 60 people have died in India as the country is battered by floods and landslides caused by heavy monsoon rains.

Some 45 people lost their lives in monsoon-related incidents in the worst-hit northern state of Uttarakhand, near the Chinese border, and casualties have also been reported in Himachal Pradesh and Uttar Pradesh.

"We are unable to confirm the number of deaths since most of the communication lines have broken down across the state," Uttarakhand's minister for disaster and relief, Yashpal Arya, told AFP. "But at least 60 people are feared dead and nearly 50,000 are stranded."

Local media reports set the death toll at 73.

Most of the people stranded are Hindu pilgrims who were heading to Himalayan shrines when they were caught by the record monsoon downpours, which have triggered landslides and the collapse of a number of bridges.

Rescuers have been helped by military helicopters to evacuate the area after the pilgrims were cut off.

The seasonal monsoon hit Kerala in the south of India on time last week, but then quickly swept northwards, covering the whole country a month ahead of schedule.

In Uttarakhand's capital of Dehradun, 37cm of rain fell in just 24 hours between Sunday and Monday morning, setting a new city record, according to the India Meteorological Department.

Some 175 houses were damaged across the state. Video footage posted on YouTube shows a three-storey building crumbling before collapsing into the flooded river.

Relief camps have been set up to accommodate people evacuated from the worst-hit districts.

Monsoon downpours usually last from June to September and account for 70% of India's annual rainfall, making them critical to the country's farming output.