A third offshore helicopter operator has suspended its use of the aircraft which ditched in the North Sea with 19 people on board.

The oil workers and crew were safely rescued when the pilot of the EC225 Super Puma was forced to land off Shetland yesterday afternoon.

Operator CHC suspended its use of the model and was followed by the firm Bristow Helicopters. Bond Offshore Helicopters has now said it has halted flights by the aircraft.

A spokeswoman said: "Due to ongoing investigations into the incident, Bond Offshore Helicopters have taken the decision to delay a return to operations of the AS332L2 and EC225 Super Puma helicopters until more detailed information is available.

"We are continuing to work closely with other operators, and the aircraft manufacturer Eurocopter, whilst also updating our customers on a regular basis."

The helicopter was carrying an oil crew from Aberdeen to a rig 86 miles north west of Shetland when it ditched at around 3.30pm yesterday.

The 17 passengers and two crew were taken from their liferaft by a rescue craft launched from the Nord Nightingale vessel, which was close to the scene. They were taken back to the tanker and flown by RAF and Bond rescue helicopters to Kirkwall in Orkney. No one was injured.

The passengers and crew were expected to fly into Aberdeen later today.

The helicopter was still floating on the sea on Tuesday, Shetland Coastguard said, awaiting pick-up by the vessel Olympic Zeus.

Nick Mair, regional vice president of western North Sea at CHC, said: "CHC's primary objective is always the safety of our passengers and people, and our pilots took actions today consistent with that commitment. We are delighted that our passengers and colleagues are safe and no one was injured.

"We think that the right thing to do is hold all scheduled flights using Super Puma/EC225 aircraft pending receipt of further technical information."

A team from the Air Accidents Investigation Branch is travelling to the north east of Scotland to determine the cause of the incident.

A spokesman for Eurocopter, the French company which manufactures the Super Puma EC225, said it is investigating the incident with the operator and authorities "with the highest priority".

He said: "Eurocopter is not able to further comment at this stage and is mobilising a team of specialists to provide additional support alongside its existing personnel in Aberdeen."

The ditching is the fourth serious helicopter incident in three years.

In May all 14 passengers and crew members on a Super Puma helicopter were rescued after it ditched about 30 miles off the coast of Aberdeen. It was on a scheduled flight from Aberdeen Airport to a platform in the North Sea.

Sixteen people died when a Super Puma plunged into the sea off the Aberdeenshire coast on April 1 2009. The gearbox of the Bond-operated helicopter failed while returning from the BP Miller platform.

The tragedy happened about six weeks after another Bond Super Puma with 18 people on board ditched in the North Sea as it approached a production platform owned by BP. Everyone survived the accident.

A union official now wants operators to provide more safety assurances to offshore workers.

RMT offshore organiser Jake Molloy said: "The primary issue for the helicopter operators, in this case CHC, is to provide information as soon as possible about what forced this aircraft down, as it's the fourth event involving the EC Puma-type aircraft.

"There is inevitably going to be questions and concerns and we need to provide assurances, not just to the workers but to their families, that the primary means of transporting them to and from work is safe."

A spokesman for CHC said the 19 passengers and crew involved in the ditching have returned to Aberdeen.

"We are delighted that everyone is back in Aberdeen and that no one was injured.

"Following a detailed debrief with the crew and technical experts, CHC is continuing to delay all scheduled commercial flights on Super Puma EC225 aircraft.

"An investigation team from the Air Accidents Investigation Branch, with CHC's full participation, has begun an inquiry into the cause of the incident. Recovery of the EC225 aircraft is under way via tug boat."