At least 21 people were killed and a further 10 feared dead after a passenger bus plunged into a fast-flowing river in central India, police said Thursday.

The bus crashed into the river when trying to cross a flooded bridge in the state of Madhya Pradesh on Wednesday evening.

"The rescue work is ongoing and specialist teams are at the scene searching for bodies washed away by the water," local inspector general of police Pawan Jain told AFP by telephone.

"We have found 21 bodies, 40 people have been rescued and 10 are still missing, feared dead. About 70 people were on the bus."

The crash occurred at a crossing of the Bagdi river in Dewas district, about 100 kilometres (60 miles) from Bhopal, the state capital of Madhya Pradesh.

The bus was removed from the river using cranes, police said, adding divers were looking other victims.

India has the highest annual road death toll in the world, according to the World Health Organization, with accidents caused by speeding, careless driving, poor roads, overcrowding and poor vehicle maintenance.