Around 500 workers on a North Sea oil platform were today involved in a massive evacuation after a security alert.

Five RAF and a number of coastguard helicopters were involved in the operation.

Sources said the evacuation followed a "significant security alert" regarding a "device" on board the Safe Scandinavia, 175 miles north-east of Aberdeen.

The alert is understood to involve an individual rather than an organisation. It is not thought to be a terrorist incident.

The evacuation involves around 500 people on board, except for a few specialists who are currently carrying out a search to discover if there is an explosive device on board.

It is understood the evacuation of one of the largest platforms in the North Sea comes after a phone call to the emergency services. Sources said the alert was sounded at 9.15am on the rig following an incident involving a woman on board.

The evacuation is being coordinated by Aberdeen Coastguard and the Air Rescue Coordination Centre at Kinloss. Lifeboats and rig support vessels are also believed to be taking part in the evacuation which is being coordinated by Aberdeen Coastguard and the Air Rescue Coordination Centre at Kinloss.

The evacuated personnel are being taken to nearby oil platforms.

The MoD said: "Five RAF helicopters in assistance to Grampian police are involved in an operation to remove 500 people from an oil rig in the North Sea."