A six-year-old boy and a man have died in hospital after they were trapped in a tourist boat that sank on the River Seine in a rare accident in the heart of Paris, police said yesterday.

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 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.

Two people, the pilot and co-pilot of a bateau-mouche, one of the long flat-bottomed barge-like boats that carry hundreds of tourists, have been placed in police custody as part of the investigation into the sinking, judicial sources said.

Authorities first said the boat had hit a pillar of the bridge, but later said it was possible it had collided with a bateau-mouche. Investigators are now focusing on the possibility of a collision, the judicial sources said.

The sunken boat was raised from the riverbed during the night, police said. It will be used in the investigations.

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