A 6-year-old child and a man have died in hospital after they were trapped in a tourist boat that sank on the River Seine in the heart of Paris, police said on Sunday.

The accident took place on Saturday night at the Pont de l'Archeveche, a bridge that connects the tip of the Ile de la Cite, where Notre Dame cathedral is located, to the Left Bank of the river.

Ten other passengers on the small boat jumped into the river before it sank and were quickly fished out.

Divers pulled the child and man from inside the sunken boat minutes after the sinking and rescuers tried to resuscitate them, but police said the attempts failed.

The nationalities of the victims were not known.

The boat was raised from the riverbed during the night, police said. It will be used in investigations into the cause of the accident, which was unclear.

Authorities first said the boat had hit a pillar of the bridge, but later said it was possible though not certain it had hit a "bateau-mouche", one of the long flat-bottomed barge-like boats that carry hundreds of tourists up and down the river.

Tourist boats ply the busy Seine day and night and accidents are extremely rare.