BP has shut down one of its oil platforms, about 75km to the west of Shetland, because of a leak.
Oil was released into the water from the Clair platform on Sunday morning.
The size of the leak is unclear, and efforts are under way to ascertain whether it has caused damage to the environment.
BP said it was caused by a “technical issue” and an investigation into what happened was under way.
No-one was injured. It was not clear how long the platform would remain shut down.
A BP spokesman said: “The Clair platform, which is located 75km (46 miles) west of Shetland, has been shut down and the release has been stopped. All personnel have been accounted for and there are no injuries.
“We are investigating the cause of the technical issue and monitoring the situation. All relevant authorities have been informed.”
The UK Government’s Department for Business, Energy and Industrial Strategy has been informed and the industry funded organisation Oil Spill Response Limited (OSRL) has also been notified.
Lang Banks, director of environmental charity WWF Scotland, said the incident highlighted “the dangers posed on a daily basis” by oil and gas operations off the coast of Scotland.
He added: “In the interests of protecting the marine environment, it’s important that we understand just how much oil has leaked.
“The platform should certainly not be allowed to restart operations until a full investigation into this incident is completed.”
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