North Sea operator CNOOC is working to tackle a Covid outbreak on board its Scott platform.
At least three people on board have contracted the virus, while around 10 others are being quarantined, according to two sources.
CNOOC has been asked to comment.
It is understood that Covid testing is being arranged for workers remaining on board the CNOOC installation, which lies around 115miles north-east of Aberdeen in the North Sea.
It comes amid further cases of the virus onboard UK installations since the start of the month.
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