Climate activists will use direct action to try to shut down major fossil fuel sites across the world in May, including the UK’s largest opencast coal mine in south Wales.

The dozen international sites facing civil disobedience from the Break Free 2016 campaign span the globe from the US to Australia and South Africa to Indonesia.

The Ffos-y-fran opencast mine, near Merthyr Tydfil in Wales, is about halfway through extracting 11m tonnes of coal. Ellie Groves, from the Reclaim the Power network, said: “The only way we can stop catastrophic climate change is taking action to keep fossil fuels in the ground.”

“The local community have battled Ffos-­y-­fran for nearly a decade and now face the threat of a new mine next door at Nant Llesg,” said Groves. “Enough is enough. We need a ban on opencast coal mining across Wales, and the rest of the UK.”

Coal is the most polluting fossil fuel and scientists estimate that 80% of current reserves must remain in the ground in order to avoid dangerous climate change. The UK government intends to phase out coal burning by 2025 but the International Energy Agency still forecasts growth in the global demand for coal.

A statement from Reclaim the Power said: “Hundreds are expected to set up camp nearby and take part in a mass action to close the mine. The action will take place a few days before the Welsh assembly elections on May 5.”

The Reclaim the Power network has held annual camps since 2013 and has conducted a series of direct actions, including blockading a World Coal Association conference and a fracking company. Ffos-y-fran supplies the Aberthaw power station, whose illegally high levels of pollution have led the EU to take the UK to court. Miller Argent, the company running Ffos-y-fran, and the local Labour MP Gerald Jones both declined to comment on the planned protests.

Campaign group 350.org, which had led the fossil fuel divestment movement, is helping to coordinate the international actions. “We’re mobilising to shut down the world’s most dangerous fossil fuel projects and support the most ambitious climate solutions,” says the Break Free 2016 website.

“We want to ensure there continues to be momentum to keep fossil fuels in the ground and to confront fossil fuel companies,” said Will Bates, global campaigns director for 350.org.

Bates emphasised that, while involving civil disobedience, the protests would be peaceful. “Our actions must reflect the scale and urgency of this crisis,” says the website. The protests are likely to emulate a protest in Germany in August 2015 which shut down the large Garzweiler opencast coal mine for a day.

“We need to be disrupting business as usual if governments will not put in place the policies that will get the job done,” said Bates. “It is what is necessary. We think it is in everybody’s best interest.”

Benjamin Sporton, CEO of the World Coal Association, said: “It is clear that coal will be a critical energy source for the long term. The coal industry is already investing to improve the environmental performance of coal. In our view the focus should be on speeding this deployment up.”

No details have been revealed about the targets of the international campaign which will take place from 4-15 May. The countries named are Germany, Spain, Turkey, Israel and Palestine, Indonesia, Phillipines, Nigeria, South Africa, Canada, US, Brazil and Australia.

