"The pilot did report that he was having some technical malfunction and was turning back to St John's," Burt told a news conference.

He had no information on the survivor's condition.

Hercules aircraft, Cormorant helicopters and surface ships were in the area trying to find survivors in the near-freezing water, said Denis McGuire of the Joint Rescue Co-ordination Centre in Halifax, Nova Scotia.

"The search effort is going on right now," he said.

Rescuers said water temperatures were just above freezing, with waves of up to three metres.