Energy giant finds source of offshore gas leak The Elgin platform leak is not underwater, energy firm Total says Total evacuated the rig in the North Sea after the leak on Sunday Experts are deciding whether leak will stop on its own, or if action is needed Initial fears of an explosion may be unfounded, an oceanographer says London (CNN) -- Energy giant Total has located the source of a gas leak on an offshore oil platform in the North Sea, the company told CNN on Thursday. The leak is not underwater, but is on the deck level of the well head platform, Total said. The Elgin platform sprang a leak on Sunday, forcing the evacuation of the rig. Experts are now working to decide whether they can wait for the gas to stop leaking on its own, or whether the company must drill a relief well or fill it with mud in a "kill operation," Total said. Nearly 240 workers were taken off the rig as the problem developed Sunday, Total said earlier in the week. The leak seems to have started as workers were sealing the well in the North Sea, about 150 miles (240 km) east of the Scottish city of Aberdeen. "Ironically, it sounds as if, just like with the Deepwater Horizon, they were closing off a well and somewhere along the line something went wrong," oceanographer Simon Boxall said, referring to the major BP oil spill in the Gulf of Mexico in 2010. The Elgin leak has echoes of the BP Deepwater Horizon spill, but there are significant differences. Total's share price was down about 2% in trading in France on Thursday afternoon. The French company's share price fell 7% Tuesday on news of the leak, but market analyst firm Jeffries International said Wednesday that it thought the market had overreacted. A union representing workers on the rig warned Wednesday that there was an "urgent need" to stop the leak. "This is an unprecedented situation and we really are in the realms of the unknown," Molloy said. But oceanographer Boxall said the risk of explosion may not be as high as initially feared. Total confirmed there was a "sheen on the water in the vicinity of the platform," but said Tuesday there was no indication of environmental damage. Shell partially evacuated two of its nearby platforms, Shearwater and Hans Deul, as a "purely precautionary" measure, it said Wednesday. CNN's Bharati Naik contributed to this report.