NORWEGIAN investigators have said that a helicopter crash which killed a Scottish man and 10 other passengers and two crew members was "almost certainly" caused by a technical fault.

Norway's Accident Investigation Board (NAIB) has launched a probe into the tragedy, which happened in the North Sea last Friday when an Airbus H225 Super Puma crashed after picking up passengers from an oil platform.

Kaare Halvorsen, aviation director of the NAIB, said that it is unlikely that the disaster was caused by human error and that it is believed that something went wrong with the aircraft's systems.

Some of the victims' families have chosen not to identify them publicly. The Scottish victim has been named as Iain Stuart, from Laurencekirk in Aberdeenshire.

Mr Halvorsen said: "On the basis of the facts we have, this involves a technical fault; it isn't human error", adding that his team are "as certain as they can be" that a technical problem caused the crash.

Mr Halvorsen said that the crew had no time to send an emergency message before the the helicopter smashed into the rocky shoreline of Turoey, a tiny island outside Bergen.

Norwegian television showed footage of what appeared to be a helicopter rotor blade spiralling down minutes before the crash en route to Bergen Airport in Flesland.

Mr Halvorsen told Norway's VG website that there had been less than one second between the fault appearing and the flight recorder coming to a halt. The recorder is thought to have stopped working when the rotor became detached.

But he stressed that the investigation, which involves British and French experts, was at an early stage and no conclusions could yet be drawn.

Footage of the crash showed the helicopter's rotor detached from the body of the aircraft and spinning through the air.

A warning light had come on in the cockpit of the helicopter on two occasions in the days before the crash, resulting in two components being changed.

The Super Pumas remain grounded in both Norway and the UK, though their manufacturer, Airbus, said on Monday that it was no longer recommending a blanket ban on their use. It insists the fleet is safe.

The Offshore Co-ordinating Group, which co-ordinates trade union policy and campaigns in the oil and gas sector, released a statement calling for the H225 helicopter to be grounded until the cause of Friday's crash was established.

"Workers in both the Norwegian and UK sectors must have genuine guarantees from regulators before flights in this aircraft can be considered," said group chair Tommy Campbell.

"Statements from manufacturers and operators will not suffice."

The family Mr Stuart have said they are "heartbroken" by his death. A statement released by relatives of the 41-year-old said: "We as a family are devastated at the loss of Iain in Friday's tragic helicopter crash in Norway.

"Iain was a loving husband and devoted father to his two children and as a family we are heartbroken. He was a caring son, brother, uncle and friend to many.

"We are appreciative of all the messages of support and kind thoughts.

"We now ask, as a family, that we are allowed some privacy at this difficult and sad time to grieve and come to terms with our loss."

Mr Stuart, from the town of Laurencekirk, worked for Houston-based oilfield services company Halliburton, which lost three other employees on board the craft.