The Amman Valley could see a return to coal in the future – should Labour leadership hopeful Jeremy Corbyn secure control of the party.

Mr Corbyn said modern technology could transform the industry and make a return to mining a viable option for Wales.

The 66-year-old MP for Islington North has emerged as the shock favourite to become leader of the party following Ed Milliband’s departure in the wake of the humiliating General Election defeat in May.

The staunch left-winger has called for a the re-nationalisation of the major power companies and told Greenpeace’s Energy Desk that he would not rule out rekindling the Welsh coal industry.

The Amman Valley boasts some of the highest-quality anthracite coal on the planet.

Mr Corbyn said: “The last deep coal mines in South Wales have gone but it’s quite possible that in future years coal prices will start to go up again around the world.”

He said there may come a time when “there will be a case for what is actually very high-quality coal being mined again”.

“I’ve looked at it, I’ve discussed it, I’ve heard about it,” Mr Corbyn said. “It’s complicated.

“At one level it looks very expensive, but the advantages also look attractive.

“If there’s to be substantial coal-fire generation it’s got to be clean-burn technology. It’s got to have carbon filters on it: it’s got to be carbon neutral.

“The principles have to be that we’re protective of our environment, guaranteeing affordable energy supplies for everybody, and we’re not ripped off by big companies.”