MUMBAI: Rescuers in India combed through mud and debris Saturday in a desperate search for survivors as the death toll from heavy monsoon rains climbed to 76, with nearly 90,000 others evacuated.

Torrential downpours have lashed India's western coast in recent days, leaving dozens missing near the financial capital Mumbai and causing the worst floods in decades in the resort state of Goa.

"People have lost virtually everything," said Goa's health minister Vishwajit Rane, pointing out that the state had not seen such heavy rains in half a century.

He said more than 1,000 houses had suffered serious damage in the area as rising waters flooded homes.

Goa's floods were its worst in decades, according to its chief minister Pramod Sawant, who said the monsoons had caused "widespread damage" but no casualties, unlike in neighbouring Maharashtra state, where 76 people died.

More than half of the deaths occurred in hard-hit Raigad, south of Mumbai, where landslides buried dozens of houses, killing 47 and with another 53 feared trapped under layers of mud.

The downpour caused the Savitri river to burst its banks, leaving the town of Mahad completely inaccessible by road, and prompting terrified residents to climb onto rooftops and upper floors to escape swelling waters.

National Disaster Response Force teams could not land their choppers in the area due to bad weather on Friday but were eventually able to rescue locals as waters began to recede.

The hillside resort of Mahabaleshwar recorded nearly 60 centimetres (23 inches) of rain in a 24-hour period ending Friday morning, the India Meteorological Department said.

Rescue teams and military units worked frantically to evacuate stranded people but their operations were hampered by landslides blocking roads, including the main highway between Mumbai and Goa.

Water levels rose to nearly 20 feet (6 metres) on Thursday in areas of Chiplun, south of Mumbai, after 24 hours of uninterrupted rain submerged roads and homes.

"Contact from the town was completely cut off due to land routes being inundated," the Maharashtra state government said.

Seven naval rescue teams equipped with rubber boats, life jackets and lifebuoys were sent to the affected areas, along with specialist divers and a helicopter to airlift marooned residents.

Nearly 90,000 people have been evacuated in Maharashtra so far.

India's weather bureau has issued red alerts for several regions in the state and forecasts heavy rainfall to continue for the next few days.

Flooding and landslides are common during India's treacherous monsoon season, which also often sees poorly constructed buildings and walls buckling after days of non-stop rain.

Four people died before dawn on Friday when a building collapsed in a Mumbai slum, authorities said.

The incident came less than a week after at least 34 people lost their lives when several homes were crushed by a collapsed wall and a landslide in the city.

Rainwater also inundated a water purification complex in Mumbai last weekend, disrupting supply "in most of the parts" of the megacity of 20 million people, civic authorities said.

Roxy Koll, a climate scientist at the Indian Institute of Tropical Meteorology, said the monsoon flooding was "unprecedented, but not unexpected".

"We already see a threefold rise in widespread extreme rains that cause floods across India," he tweeted.

Climate change is making India's monsoons stronger, according to a Potsdam Institute for Climate Impact Research report published in April that forecast dire consequences for food, farming and the economy affecting nearly a fifth of the world's population.