Guwahati, India: Rescuers were searching on Tuesday for about 20 people feared missing after a boat capsized and sank in a rain-swollen river in remote northeast India, a government official said.

The motorised ferry was taking about 100 villagers to a popular boat race in Assam state when it hit a bridge pylon and overturned on the Kolohi river late on Monday, a top district administrator told AFP.

"The village headman who jumped out first from the boat told us that some 80-90 of his fellow passengers swam to safety," said Vinod Seshan.

"There are apprehensions about some 20 other people but no one has reported any person missing to the police as yet. But we have restarted rescue operations this morning," he told AFP.

Initial reports said up to 50 people were feared missing, but district police chief Indrani Barua said most passengers were later thought to have swum to safety.

Ferries plying rivers in India's remote northeast do not keep passenger lists, making it impossible to find out the exact number of people missing after a boat accident.

Boat accidents are common because of lax safety standards and overcrowding.