© Antoine Agasse/AFP/Getty Images file
A file picture taken on May 29, 2009 shows the Total Elgin-Franklin oil and gas platform in the North Sea 150 miles off Aberdeen on Scotalnd's east coast.
A cloud of explosive natural gas boiling out of a leaking drilling platform off the Scottish coast has led to the evacuation of hundreds of workers and the creation of a two-mile exclusion zone.

Coastguard officials ordered shipping to come no closer than two miles from the abandoned Elgin platform, located 150 miles off Aberdeen, and said there was a three-mile exclusion zone for low-flying aircraft such as helicopters, the BBC reported.

Energy firm Total UK, which operates the platform, said it did not know the source of the leak and was considering all options including drilling a relief well - a solution that could take six months.

"We have mobilised experts from elsewhere in the Total Group to offer additional assistance and help us deal with the incident," it said in a statement.

It evacuated 238 workers from the platform after the leak was spotted on Sunday, according to a report in The Scotsman. The report said Shell had reduced its workforce on two nearby offshore installations because of the drifting gas.

Reuters reported that the company has enlisted the services of Wild Well Control, which was heavily involved in the BP's Deepwater Horizon oil spill in the Gulf of Mexico in 2010.

In a statement, Britain's Department for Energy and Climate Change said the environmental impact of gas condensate leaks is substantially lower than from oil spills.

Aerial surveillance flights have confirmed the presence of a sheen on the water, which is thought to be gas condensate, a petrol-like substance that normally evaporates naturally.

Workers' union leader Jake Molloy warned there was there was the potential for a "major event" if the gas ignited.

"You're looking at something on the scale of Piper Alpha here," he told Scottish channel STV, referring to the huge 1988 oil rig blaze that killed 167 workers. "On the positive side, nobody's there. So the human side has been dealt with. But the potential remains for an ignition source and for the complete destruction of that installation."

Reuters contributed to this report.