A 23-year-old British woman is being questioned by Grampian Police following a major security alert on North Sea oil rig.
More than 500 workers were airlifted from the Safe Scandinavia following a bomb threat made by a woman on the rig, sources said. It is not believed to be terrorism-related.
It is understood personnel are now returning to the installation.
A police statement said: "Grampian Police can confirm it is meantime investigating an alleged incident on a North Sea installation. As part of the police inquiry into this matter arrangements are being made for a 23-year-old British woman to be taken on shore.
"The incident, which was reported to Grampian Police Force Control Room at 9.30am, is not considered terrorism related. The operating company took precautionary action to down man. However, it has since reversed that decision and it is understood it is presently returning personnel to the installation."
The alarm was raised on an accommodation block on the 539-man rig, which is attached by bridge to an oil rig in the Britannia field.
Fourteen helicopters, including five from the RAF, airlifted workers from the rig, 115 miles north east of Aberdeen.
The accommodation block was evacuated and the workers moved across the bridge on to the rig after the alarm was raised.
Oil company Britannia Operator Limited said reports were being investigated of an incident involving the "flotel" Safe Scandinavia, which is located on the Britannia Field.
"The relevant emergency authorities have been alerted and a company response team is assisting in the co-ordination of support services," it said in a statement. The company is doing everything possible to resolve the situation and to confirm details of the incident."
