Norwegian oil and gas producer Statoil said on Friday it had evacuated the Gullfaks C platform in the North Sea after changes in well pressure led to a fault on one of two valves designed to prevent a blowout.

Environmental group Bellona said the situation was “very critical” and highlighted continued risks of offshore oil and gas exploration in the wake of BP’s well blowout and environmental disaster in the Gulf of Mexico.

“There are no leaks and no injuries,” Statoil spokesman Gisle Johanson said. “The situation on the platform is stable and we are planning for further operations to normalize the situation.”