Statoil said it has 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.

The evacuation of about 90 people was caused by an “unstable pressure situation” in a Gullfaks well, which meant “too much or too little” pressure, according to Statoil spokesman Gisle Johanson.

“There are no leaks and no injuries,” Johanson said, adding that the situation on the platform is currently stable.

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, reports Reuters.

Gullfaks is an oil and gas-producing field in the Tampen area of the Norwegian section of the North Sea. It produces 78,000 barrels of oil per day and 420 million standard cubic metres of gas per year.