Torrential rains and flash floods washed away homes and roads in north India, leaving at least feared 60 people dead and thousands stranded, as the annual monsoon hit the country earlier than normal, officials said Tuesday.

Authorities called in military helicopters to try to rescue residents and pilgrims cut off by rising rivers and landslides triggered by more than three days of rain in the Himalayan state of Uttarakhand, officials said.

"We are unable to confirm the number of deaths since most of the communication lines have broken down across the state," the state minister for disaster and relief said.

"But at least 60 people are feared dead and nearly 50,000 are stranded," Yashpal Arya told AFP.

Among those killed were four members of the same family, who died when their home was hit by a landslide as they slept, in Kasta village near the state capital of Dehradun, local officials said.

Television footage showed bridges, houses and multi-storied buildings crashing down and being washed away by the swirling waters. A swollen river is seen engulfing a giant statue of Lord Shiva in the tourist hub of Rishikesh.

Rising water levels in some towns have also swept up cars, earthmoving equipment and even a parked helicopter, as a result of the surprise rains which have lashed the state since Saturday.

Roads in many areas have been destroyed, leaving hundreds of pilgrims stranded on their way to visit shrines in remote areas. Authorities have cancelled pilgrimage trips, fearing further rains and landslides in the state, often referred to as the "Land of the Gods" because of its many Hindu temples and other sites.

Fresh rains in some districts were hampering rescue efforts, with teams from the national disaster management authority camping in the popular pilgrimage town of Haridwar awaiting air lift to the worst-affected districts, officials said.

The state government was also readying food parcels and drinking water to be dropped by helicopters to remote villages.

"The situation is very grim. The meteorological office has predicted that the rain will continue for another three days at least," government official Amit Chandola was quoted by television stations as saying.

The annual monsoon, which India's farming sector depends on, covers the subcontinent from June to September, usually bringing some flooding.

But the heavy rains arrived early this year, catching many by surprise. The country has received 68 percent more rain than normal for this time of year, data from the India Meteorological Department shows.

In the neighbouring state of Himachal Pradesh, at least 10 people were feared dead, while more than 1,500 tourists were stranded, a local official told AFP.

Efforts were under way to try to reopen the major roads to rescue those cut off by the rains, said J. M. Pathania, a top administrative official of Kinnaur district.

Two hydropower stations in the state that cater to the northern Indian grid have also been shut down.

A few villages close to the border with China have seen unseasonal snowfall, leaving dozens of shepherds and thousands of sheep stranded, a village headman told AFP.

Over the border in Nepal, at least 12 people have been killed in landslides triggered by monsoon rain over the last three days, officials said.

Seven members of the same family, including five children, were killed after a landslide buried their house in a remote village in northwestern Nepal, Prakash Gharti Magar, a local police officer told AFP.