New York  - A helicopter with five Italian tourists on board collided with a light aircraft over New York's Hudson River Saturday, sending wreckage from both plunging into the waters.

All nine people on board the two aircraft were assumed dead, Mayor Michael Bloomberg said in broadcast remarks. Two bodies had been recovered, and several bodies were in the wreckage of one of the craft that had been spotted.

Divers were searching in the murky 10 metre-depths of the swift- flowing Hudson River for other bodies, Bloomberg said.

"The accident was simply not survivable," Bloomberg said.

The helicopter had taken off from the 30th Street helipad for a sightseeing tour, CNN reported.

The light aircraft with three people on board, including the pilot, had taken off from a nearby airport and was headed to the New Jersey beach. (dpa)