Around 160 workers were airlifted from an accommodation block attached to a rig in the Britannia field north east of Aberdeen on Sunday after the false alarm.

The massive rescue operation was prompted by suggestions that a device was on board the Safe Scandinavia installation.

An investigation later found nothing suspicious.

A 23-year-old woman was taken off the rig for questioning and has been arrested in connection with the incident.

A Grampian Police spokesman said: "The female is expected to appear at Aberdeen Sheriff Court on Monday in connection with the matter."

The 161 workers who were flown to neighbouring platforms returned to the Safe Scandinavia on Sunday night.

Police, coastguard and RAF teams were all involved in the major security alert.

Oil company Britannia Operator Limited said normal operations would be restarted as soon as possible.

Managing director Kathy McGill said: "We are very relieved that this has turned out to be a false alarm, but we obviously had to treat it seriously and act appropriately to ensure the safety and wellbeing of all our people."