( BBC ) - Police are making arrangements to fly a 23-year-old woman from a North Sea oil platform which was at the centre of a security alert.
The British woman, who had been working aboard the installation, was detained by the offshore installation manager. She is thought to have been sedated.
The alert meant 161 staff were taken off the Safe Scandinavia platform.
Owner Britannia Operator Ltd said a worker had made allegations about a possible suspicious device.
The firm confirmed that the "precautionary downman" had been halted.
A total of 539 people had been on board the Safe Scandinavia - which is an accommodation installation attached by a bridge to an oil rig in the Britannia field.
Britannia Operator Ltd said in a statement the Britannia platform would remain shut down, but normal operations would be restarted as soon as possible.
The statement added: "The downman occurred following allegations by a worker on the Safe Scandinavia that there was a possible suspicious device on the flotel."
"A thorough search of the Safe Scandinavia has revealed nothing suspicious and it has now been deemed safe for workers to return to normal operations.
"The 161 workers who had been earlier flown to the neighbouring Alba and Armada platforms are now returning to the Safe Scandinavia."
The statement added that all those involved in the incident were safe and unhurt and the installations were secure.
Grampian Police are now on their way to the field to investigate the incident but said they did not consider it to be related to terrorism.
Kathy McGill, Britannia Operator Ltd's managing director, 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."
The company said the platform remains shut down but normal operations would be restarted as soon as possible.
The accommodation platform is 130 miles off the Aberdeen coast.
Scotland's Justice Secretary Kenny MacAskill was being kept informed about the operation.
A Scottish Government spokeswoman said: "A Scottish Government civil contingencies official is based in the Grampian Police control room, and the justice secretary is being regularly kept appraised of developments.
"There are well established procedures for dealing with incidents in the North Sea, and these are operating efficiently and effectively."