Shell has briefed staff about its internal inquiry into September's tragedy on Brent Bravo.

Sean McCue, 22, from Fife, and Keith Moncrieff, 45, from Tayside, suffocated after the gas escaped.

The offshore union OILC said the two workers had been cleared of blame by the company.

Their families say they are still seeking answers about why their loved ones died.

They have asked Shell why the men were in the leg of the platform after a main alarm had been set off.

No comment

Mr Moncrieff's brother Derek said: "I wonder why it took them so long to get my brother out? When the alarm went off my brother was still there five to eight minutes afterwards."

The company, which is not making the findings of its internal inquiry public, has so far made no comment on the relatives' concerns.

Some of the offshore workers who were briefed on Thursday have passed on the main conclusions to the OILC union in Aberdeen.

Derek Moncrieff lost his brother Keith

In October, Shell denied suggestions from workers in the Brent Field that the company's interim report appeared to blame the two men for the accident.

The Brent Bravo is one of four oil production and storage platforms in the UK northern sector of the North Sea that make up the Brent field.

Two of its legs are flooded with sea water. The third, the utility shaft, contains process equipment and allows access to the top of the storage cells.

Shell says it will not comment on the issue while the Health and Safety Executive is continuing its investigations.

The HSE says it will be submitting a report to the procurator fiscal at Christmas.