Climate campaigners have challenged a claim by the Albanese government that it has not approved any new coalmines in 2024, saying a Queensland mine given a green light this week was a new development.

The environment minister, Tanya Plibersek, approved four coalmine projects on Thursday, describing them all as expansions of existing mines that would mainly be digging up coal to make steel.

On social media, the minister wrote: “In 2024 Labor has approved 0 new coalmines.”

But the comments have infuriated climate campaigners, who say Vitrinite, the company behind the Vulcan South mine in Queensland, one of the four projects approved, has itself described the project as independent from a neighbouring mine.

Vitrinite’s environment report on the project, published in October, said its Vulcan South mine and its existing Vulcan mine were “approximately 10kms apart” and were “independent projects.

Vitrinite said in the report that Vulcan South, which is intended to operate until 2033, was a “greenfield development” and “is not part of a staged development and is not part of a larger project”.

The company has said its plans would see the loss of 1,166 hectares of koala habitat, and would affect the habitat for the greater glider, squatter pigeon and a threatened ecosystem dominated by brigalow trees.

Claire Gronow, a coordinator for campaign group Lock the Gate, said: “Vitrinite says this is a new mine. We were disgusted when we saw those social media posts. We’re gobsmacked.”

Jenny Brown, a climate campaigner at Queensland Conservation Council, said: “It’s hard to agree that there are no new coalmines being approved.”

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Plibersek attempted to downplay the decisions to approve the four mines, saying the mines were extensions and the coal would be used for steelmaking and that there was “currently no feasible renewable alternatives for making steel”.

On Friday the climate change and energy minister, Chris Bowen, also said the projects were part of “existing mines”.

A spokesperson for the minister said: “The independent scientific experts and the minister’s department classify the [Vulcan South] project as an expansion.”

Climate groups estimate the four approved coal projects would release more than 880m tonnes of CO2 across in their lifetimes – the equivalent of almost double Australia’s annual emissions – most of which are released when the coal is burned overseas.

Three coalmine expansions approved in September would release about 1.3bn tonnes of CO2, campaigners said.

Brown claimed the government was trying to “greenwash” its decisions.

“Climate change does not care about technicalities, or whether this is an extension or a new mine – they have the same implications for the country, the environment and our wildlife,” she said.

Prof Lesley Hughes, a councillor at the Climate Council, said: “Our atmosphere doesn’t care if this coal is for steel or power – it’s all heating our planet and driving climate pollution. Burning coal fuels the climate crisis, worsening bushfires, floods and heatwaves that devastate our communities. This decision flies in the face of science, common sense, global responsibility and our duty to protect our kids’ future.”

On Friday, climate activist Zack Schofield, of the Rising Tide group, was filmed spray-painting the word “LIAR” on the glass front of Plibersek’s electorate office in Redfern, Sydney.

Schofield said he would hand himself in to police, saying his actions were a response to the coalmine approvals.

Plibersek said a member of her staff was inside at time the office was sprayed.

She said: “Australia is a great democracy. It’s terrific that we are free to disagree with governments, and with each other. But the way we disagree matters. It should be peaceful, respectful and lawful.

“This kind of vandalism and intimidation is completely unacceptable. We all have a duty to call it out, wherever it happens.

“All morning, my hardworking staff have been giving statements to the police instead of helping local residents with things such as Medicare, Centrelink and disability matters, like they usually do.”