Massive California gas leak permanently capped

A gas well leak that spewed tons of methane into the environment and forced thousands of Los Angeles residents from their homes has been permanently capped, state officials said.

The announcement confirmed earlier reports by the Southern California Gas Company (SoCalGas) that a leaking well at its facility in Porter Ranch had been plugged.

The news put an end to a four-month-long drama that saw thousands of Porter Ranch residents sickened by the fumes and forced to relocate to other areas of Los Angeles.

"We have good news," Jason Marshall, deputy head of the California Department of Conservation, told a news conference on Friday.

"We have confirmed that the leak of gas has been capped. We have the gas emissions under control."

He said the damaged well was sealed with concrete, putting it permanently out of service.

The leak, first detected on October 23 last year, at the gas company's Aliso Canyon facility, has been described as an environmental disaster.

Methane, which is colourless and odourless, is a much more potent greenhouse gas than carbon dioxide.

But public health officials and the gas company -- a division of Sempra Energy -- have said the fumes posed no danger to Porter Ranch residents.

The gas company is facing a series of lawsuits, as well as criminal charges brought by the Los Angeles District Attorney's Office, which alleges SoCalGas failed to immediately report the leak.

However, the company insists it broke no laws and its president, Dennis Arriola, said on Thursday it was in the process of inspecting the other wells at Aliso Canyon.

"We recognise the disruption the gas leak has caused to local residents," he told reporters. "We are committed to earning back their trust and confidence over time through our actions, not our words.