Activists from environmental campaign group Extinction Rebellion, some dressed as canaries, blocked the entrance to a British open-cast mine on Wednesday to protest against plans to expand it.

The activists have promised three days of action at the Bradley mine in County Durham, northeast England, which belongs to The Banks Group.

One of the few open-cast coal mines left in Britain, the site has been operational since 2018 despite plans for the polluting fuel to be totally phased out by 2025.

Four "human canaries" in wire cages joined scores of other campaigners at the site.

"Here we are, trying to stop the coal mine because there's no need for coal."

Others wore yellow hats and scarves, chanting "we are non-violent".

They are demanding that local authorities and the government reject The Banks' request to expand the mine.

The company responded by saying coal was needed for certain industries, and that if Britain stopped producing coal, it would have to be imported from Australia and Russia.

"Five to six million tonnes of coal will still be needed each year in the UK as a raw material for our steel and cement industries, so that we can build much-needed infrastructure including new wind and solar farms, houses, roads and railways," said Mark Dowdall, from The Banks Group.

"The privileged, ill-informed XR protestors... would be more effective protesting against imports of Russian, American and Australian coal," he added.