French energy giant Total was awaiting advice on Sunday from British regulators on whether it is safe to approach a North Sea platform that has been leaking flammable gas for a week.
Britain's Health and Safety Executive (HSE) "has received a risk assesment from Total and the process of thorough examination of the documentation is taking place," an HSE spokesman told AFP.
"HSE will not speculate on how long this process will take," he added, stressing that Total does not legally need permission from the regulator to approach the Elgin rig, 150 miles (240 kilometres) from Aberdeen in eastern Scotland.
Total's chief executive had said Saturday that the firm was awaiting British agencies' authorisation to send "specialised firefighters" to the rig, which is leaking an estimated 200,000 cubic metres of highly flammable gas each day.
"We're waiting for the authorisation to send our specialised firefighters," Christophe de Margerie said at an event in Rennes, western France, according to Total's Twitter account.
"Intervention could start in around eight days," he added. A spokeswoman for Total at the company's Paris headquarters confirmed that Margerie was referring to the HSE.
Four fire ships were on standby on Sunday on the edge of a two nautical mile wide exclusion zone around the platform, while Total said it had assembled a team of experts and engineers at a makeshift crisis centre in Aberdeen.
The rig's 238 crew were evacuated after the leak was discovered last Sunday, while safety concerns have forced Total's Anglo-Dutch rival Shell to halt production at its Shearwater platform and Noble Hans Deul rig four miles away.
Total said on Saturday that a flare on the rig, which had threatened to come into contact with the low-lying gas cloud and cause an explosion, had gone out -- but that there was still a risk of ignition.
"There is still a gas escape, and clearly escaping gas is always at risk of ignition and explosion," Total's UK communications manager Andrew Hogg told AFP.
Total has seen around eight billion euros ($10 billion) wiped off its stock value since the last of Elgin's crew were evacuated on Monday.
The company is preparing to sink two relief wells to stop the gas leak, in parallel with an operation to pump so-called "heavy mud" into the stricken well at high pressure.
Explore further: Holistic soil to boost productivity