Air accident investigators have urged a safety watchdog to take swift action after new evidence emerged about a fatal helicopter crash in Norway.

Iain Stuart, 41, from Laurencekirk in Aberdeenshire, was among 13 men who died when the Super Puma went down near Bergen on April 29.

The helicopter crashed on the island of Turoey seconds after its rotor blades detached 2000ft in the air.

Inspectors from the Accident Investigation Board Norway (AIBN) are carrying out an inquiry into the accident.

They believe they have uncovered evidence of metal fatigue in the Super Puma's gearbox and warn that "the current means to detect a failure in advance are not effective."

In their latest report, published on Wednesday night, inspectors said: "It cannot be ruled out that this signifies a possible safety issue that can affect other main gear boxes of the same type.

"The nature of the catastrophic failure of the main rotor system indicates that the current means to detect a failure in advance are not effective.

"The AIBN therefore recommends that European Aviation Safety Agency take immediate action."

All commercial Super Puma H225 helicopter flights have been grounded in the UK and Norway since the incident.

The helicopter was travelling to Fresland Airport from the Gullfaks B oil field about 74 miles off the Norwegian coast when it crashed.

The aircraft shattered into pieces when it smashed into the rocky shoreline of Turoey in western Norway.

Mr Stuart's family have said they are "heartbroken" by the death of the 41-year-old father-of-two.

The ten other passengers who died were Norwegian, while helicopter operator CHC lost two pilots - a Norwegian and an Italian.