Christopher Hill, 42, died after he was seriously injured on the sea bed of the Buchan field, 70 miles north east of Aberdeen.

He was diving in about 150m of water near the support vessel Discovery late on Friday afternoon when the accident happened.

Police and Health and Safety Executive officers have set up an inquiry unit on a support vessel near the accident site.

A spokesman for Mr Hill's employers, the Aberdeen-based subsea contractor services Stolt Comex Seaway, said there will be no comment on the incident as enquiries are continuing.

Fatal accident

But he said Mr Hill's death was the first fatal accident suffered by the company for many years.

"The Discovery is one of the most modern diving support vessels in the North Sea," he said.

"The business is very well regulated these days and this accident appears to be a tragic one-off.