Two activists have 'locked on' to machinery inside the Field House opencast site owned by Hargreaves, close to West Rainton, County Durham.
They flew a banner reading "System change, not climate change" and dressed in red, which they say represents the red line for the climate that is being crossed with the continued reliance on fossil fuel extraction.
At the same time, dozens of activists entered the Bradley opencast site in north west County Durham, with banners and placards to show their opposition to the mine.
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They bore reading “Save Druridge Bay” - referring to plans for an opencast mine at the Northumberland beauty spot - and “Coal Nee More”, to show opposition to other proposed new mines in the North East of England.
Protestors said all protestors left site at 1, and no arrests took place. Work was stopped from 7 to 1 today.
Stephen Guy, from the Sherburn Labour Party and West Rainton/ Pittington against Opencast, said: "For years, along with many other former coal miners and in accordance with NUM policy, I have campaigned against opencast mining.
"This form of coal extraction is damaging to our environment and communities. It is tantamount to vandalism in pursuit of profit.
"It is shameful that central government purport to value localism yet their Inspectors and the Secretary of state ignore local people during consultations and elected Councillors who make planning decisions which, as we have witnessed twice in County Durham on recent times, are overulled at public inquries."
He added: "Our villages are far too important to us not to fight. We will not lie down and allow companies to profit at our expense."
One of those at West Rainton said: "We are at Hargreaves coal mine today and take direct action to challenge the destructive fossil fuel industry. We stand in solidarity with the locals and protectors at Pont Valley that is also in County Durham, and those on the frontlines fighting the fossil fuel industry globally."
Rachel White, one of the activists involved, said: “Our voices have been silenced, democratic procedures have failed us. We have lost hope in legal processes but continue to engage in every way possible. Direct action is fundamental to our fight for a sustainable future.”
A spokesman for Durham Police said; "Officers are responding to renewed protest at the Bradley opencast site between Dipton and Leadgate this morning, where a number of activists have entered the site.
"The A692 remains open to traffic and Durham Constabulary will not close the road unless it becomes absolutely necessary to protect public safety due to the protest activity."
There has also been opposition to plans for an opencast mine around Pittington on the Sunderland-County Durham border, in recent years.
Protestors said their actions today coincide with a global day of action against fossil fuels and climate change. Thousands of people across the planet will mobilise under the #riseforclimate banner for a possible and fair future.
This action is part of a diversity of strategies of the campaign, including a recent Judicial Review of Housing and Local Government Secretary James Brokenshire’s verdict to allow the opencast to go ahead.