OSLO (REUTERS) - Rescue services had airlifted 479 people to safety from a luxury cruise liner with engine trouble off the coast of Norway by Sunday morning (March 24) and began towing the vessel to a nearby port.

The Viking Sky, with 1,373 passengers and crew on board, sent out a mayday signal on Saturday as it drifted towards land in the Norwegian Sea.

The airlift of passengers, many of them elderly, from the Viking Cruises ship by helicopter was halted on Sunday morning as two tugboats started steering the vessel towards the nearest port.

Founder and chairman of Viking Cruises, Norwegian billionaire Torstein Hagen, said he hoped the vessel would arrive at the port of Molde on Norway's west coast by Sunday afternoon.

"They've had a bit of a shocking experience," Mr Hagen told Norwegian TV2 and other media after meeting passengers who had been hoisted one by one from the ship's deck in stormy weather.

"Most of our passengers are senior citizens ... imagine what it's like to hang there on that wire. It must be a terrible experience but they seem to have handled it very well," Mr Hagen said.

The helicopters are on standby in case the captain decides to restart the airlift, the rescue service said.

The 915 passengers were mainly from the United States and Britain, the rescue services said. There were also Canadians and Australians on board, among others, the cruise company said.

Some 20 injured passengers had been taken to hospital, Viking Cruises said, while others had only minor injuries..

One was taken to St. Olav's Hospital in the town of Trondheim, which is central Norway's most advanced medical facility. Others were taken to local hospitals in the region.

"Many have also been traumatised by the experience and need care when they arrive on shore," the Norwegian Red Cross said in a statement.

The airlift had gone on through the night.

The ship has been able to restart three of its four engines on Sunday morning but still needed assistance. The tugboats, one in front and the other behind, were towing the ship at 7 knots (13kmh). The vessel is about 80km from Molde, Norway's maritime rescue service said.

BROKEN WINDOWS

Stormy weather conditions had improved in the early hours of Sunday, with winds blowing at 14 metres per second, down from 24 metres per second previously, according to the Norwegian Meteorological Institute.

The wind speeds are expected to fall further during Sunday.

Images and film posted by passengers on social media showed furniture sliding around as the vessel drifted in waves of up to 8m, and passengers earlier described the ordeal.

"We were having lunch when it began to shake. Window panes were broken and water came in. It was just chaos. The trip on the helicopter, I would rather forget. It was not fun," American passenger John Curry told public broadcaster NRK on Saturday.

The stretch of water known as Hustadvika and surrounding areas are known for fierce weather and shallow waters dotted with reefs.

Built in 2017, the Viking Sky is 227m long and 29m wide, the Viking Ocean Cruises website said.

"We all want to know how this could have happened," company chairman Mr Hagen said. "I'm sure there will be plenty of time to point fingers at what could and should have been done, but that's for later. Something like this shouldn't happen, but it has."