Total UK has shut down oil and gas production from its North Sea Elgin/Franklin platform and evacuated staff following a gas leak on Sunday, the company said.
Production has stopped, Total UK said on Monday, adding that all 238 personnel had been accounted for and no injuries had been reported.
An aerial surveillance flight was scheduled to inspect a sheen reported in the vicinity of the platform on Monday, Total added.
The peak production capability for the Elgin/Franklin field is 280,000 barrels of oil equivalent per day, 175,000 barrels per day condensate and 15.5 million cubic metres of gas per day (mcm/d), according to Total.
The cause of the leak was still unknown and investigations were ongoing, Total said.
On Monday morning, 150 non-essential personnel had been evacuated to Aberdeen and a further 69 employees had been brought to neighbouring offshore installations.
Oil produced at the facility is exported via the BP-operated Forties Pipeline System to Kinneil in Scotland and gas flows through the SEAL pipeline to Bacton in Norfolk.
Gas flow through the Bacton SEAL terminal fell by around 10 (mcm/d) to 7 mcm/d early on Monday, data provided by UK energy network operator National Grid showed.
UK gas prices for immediate delivery traded in line with Friday's closing levels in early trading on Monday at 53.50 pence per therm, broker data showed.
(Reporting by Karolin Schaps; editing by Jason Neely)