Man arrested over 'person trapped' report

A NSW man who called police out to save a person trapped in a submerged car has been arrested.

The 34-year-old man told police on Sunday night he had been a passenger in a vehicle that had been driven into the water off a boat ramp at Port Stephens and that a person was still trapped in the vehicle.

Two officers dove into the water repeatedly to try to save the trapped person but failed to do so. Police finally winched the vehicle closer to the shore, only to discover there was no one in it.

The man was arrested and the two officers have been treated for hypothermia.