Mumbai's coastline is more used to rubbish washing ashore than dead mammals, but on Friday residents woke to the sight of a nearly 40-foot-long whale on one of its most popular beaches.

Hundreds of people descended on Juhu beach in the north of the teeming western Indian city to catch a glimpse of the Bryde's whale after it washed ashore late Thursday.

"It's 11.3 metres (37 feet) long and weighs around 20 tonnes," said Makrand Ghodke, an official at the Maharashtra Forest Department who identified the type of whale.

"There is no sign of any wounds. We think it died three or four days back and we will conduct an autopsy to determine the cause of death," he told AFP.

Ghodke said joggers had first spotted the dead mammal on Thursday night and called his department.

He added that a crane was being readied to help move the massive whale from the beach, which rests against the Arabian Sea.

This month 45 whales died after stranding themselves on a beach in Tamil Nadu in southern India.

In June, a 42-foot-long blue whale washed ashore near Alibaug, a coastal town lying around 100 kilometres (60 miles) south of Mumbai in the state of Maharashtra.

Beaches line Mumbai's coast and although extremely popular with locals and tourists, they are often home to piles of rubbish, particularly during the monsoon months when high tides spew out tonnes of waste.