Six people have been killed and 20 others injured in a head-on collision between a tractor-trolley and a speeding truck in the western Indian state of Rajasthan, police said on Saturday.

The accident occurred in the Sumirpor area of Pali district, nearly 300 kms from state capital Jaipur late on Friday night.

"The tractor-trolley was carrying pilgrims from Jaisalmer district when the speeding truck coming from the opposite direction crashed into the vehicle at high speed," a police officer told the local media.

While six of the pilgrims died on the spot in the impact of the collision, those injured have been admitted to a nearby hospital. "The condition of some of the injured is said to be serious," the officer said.

Indian Prime Minister Narendra Modi's office tweeted to express his grief over the tragedy.

"The accident in Pali, Rajasthan is saddening. In this hour of grief, my thoughts are with the bereaved families. I pray for a speedy recovery of those injured," Modi said.

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"A probe has been ordered into the accident," the police officer said.

Road accidents are common in India, with one taking place every four minutes. These accidents are often blamed on poor roads, rash driving and scant regard for traffic laws.

The Indian government's implementation of stricter traffic laws in recent years has failed to rein in accidents, which claim over 100,000 lives every year.