At least 20 people were killed and over 20,000 displaced in heavy rains that have lashed the northern Indian state of Rajasthan since Tuesday night, in what is claimed to be the heaviest rainfall in over 30 years, a senior police official said Thursday.

"So far 20 people are confirmed dead in the incessant rains that have flooded the state, including capital Jaipur. The death toll is likely to go up even though the flood waters have now started receding. More than 20,000 people are forced to leave their homes because of flooding," he said, on condition of anonymity.

Local TV channels reported that schools have been closed and rail and transport links have been disrupted in Jaipur, popularly known as the Pink City, in the wake of the rainfall, and beamed footage of people taking shelters on rooftops to avoid being caught flood waters.

Many foreign and domestic tourists have been stranded in Jaipur, a popular tourist attraction, some 250 kms from the Indian capital, the reports said.

Meanwhile, Indian Prime Minister Manmohan Singh has assured of extending all possible help to the state in the wake of the natural calamity.