OTTAWA - ONE person has been rescued, another died and 16 were missing on Thursday after a helicopter ferrying workers to an offshore oil rig crashed into the icy North Atlantic Ocean off Canada's east coast.

The downed helicopter was flying from Saint John's, Newfoundland, to the Hibernia offshore oil platform when it plunged into the ocean some 87 kilometres southeast of Saint John's at 9.18 am (7.48pm Singapore time), said officials.

One person was plucked from the frigid waters and rushed to a hospital in Saint John's, and a body was recovered hours after the crash.

Earlier, two life rafts were found floating among the debris, but there was nobody onboard, a spokewoman for the Joint Rescue Coordination Center in Halifax, told AFP. They may have been deployed manually or automatically inflated when the helicopter hit the water, officials said.

'The aircraft has sunk,' Rick Burt of charter firm Cougar Helicopters told a press conference. But 'we are hopeful and so we'll continue to search until there's no hope whatsoever,' he said.

As rescuers continued to comb the area, however, winds picked up creating waves up to three metres high, and water temperatures were near freezing (0 deg Celcius), officials said.

'We identify search patterns that we use that ensure that the entire area is covered and we do a drift assessment to determine where anything on the surface would have drifted,' Burt said.

He said the missing passengers could last up to 24 hours in the water, wearing survival gear.

A half dozen military and civilian aircraft and Canadian Coast Guard vessels were despatched to scour the area. At the onset, a military plane on a routine training mission and a merchant ship were first on the scene. Others took up to an hour to reach the crash site.

The lone survivor so far was picked up by a civilian helicopter owned by Cougar Helicopter. Since then, the company said it has temporarily suspended all of its offshore flights until it knows the cause of the crash. -- AFP