Energy group Total S.A. evacuated a platform in the North Sea on Monday after discovering a gas leak.

The company's U.K. exploration subsidiary Total E&P UK said 238 workers were moved off the Elgin platform 150 miles east of the Scottish city of Aberdeen after it sprang a leak Sunday. No one was injured.

The leak started during work to plug and abandon the well, which was no longer producing gas, the government's Department of Energy and Climate Change said.

"Total has now shut in all wells but remote monitoring has revealed that gas continues to be released," officials said in a statement.

The company said it did not yet know what had caused the leak.

A surveillance flight on Monday morning detected a sheen on the water around the platform, believed to be caused by gas condensate -- gas that contains some oil dissolved in it, officials said. Gas condensate is a lighter fuel than crude oil and a gas condensate sheen is usually less harmful to the environment than a sheen caused by crude oil, as it evaporates more quickly and does not cling to wild animals.

A gas condensate leak can still be dangerous -- a huge leak of gas condensate triggered one of Britain's worst oil disasters off the Piper Alpha rig in 1988. The leaked gas caused an explosion and several oil fires that killed 167 people.

Total said it has now stopped production at the platform which would normally produce 5.5 million cubic meters of gas per day, and 67,000 barrels of gas condensate.