Unions say their alternative plan to avoid thousands of job losses at Tata has been rejected by the steel company.

Community criticised the decision not to accept the unions’ “credible alternative” to the company’s “bad deal for steel”.

Unions met the company in London on Thursday with another plea not to press ahead with its proposals for its plant in Port Talbot, South Wales, which will lead to the loss of jobs.

Tata Steel has insisted its £1.25 billion plan for a state-of-the-art electric arc furnace in Port Talbot would be the largest investment in the steel industry for decades and would secure the future of UK steelmaking.

“It would protect the majority of jobs, reduce the UK’s carbon emissions by five million tonnes a year and could kickstart a green industrial revolution in South Wales,” said a spokesperson.

Community general secretary Roy Rickhuss said after the meeting: “It’s incredibly disappointing that Tata have chosen to reject the multi-union plan, which is an ambitious and viable alternative to their destructive bad deal for steel.

“We do not accept the company’s assertion our plan was too expensive – in fact, it would have returned the company to profits, and the additional capital expenditure needed to make it a reality could have been funded by an additional £450m from the government – a drop in the water compared to what other European countries are investing in their domestic steel industries.

“Tata have made their decision, and our members will decide on our collective response.

“Tata made a proposal to negotiate a package with the unions to give us firm assurances on jobs and future investment, and we will consult our members on how we proceed

“We want to make one thing absolutely clear to the company: this isn’t over – not by a long shot. We will never stop fighting for our jobs, our industry, and our proud steel communities.”

Members of Community and the GMB are being balloted on whether to strike over the plans. Unite members have already voted in favour of industrial action.

Community Assistant General Secretary Alasdair McDiarmid said: “Tata have made a serious mistake in rejecting the credible, expert-backed Multi-Union Plan. Today’s announcement confirms that this was never about what was best for the steel industry, the country or the long-term future of the business: it was always about short-term cost-cutting.

“With their decision today, Tata have missed an historic opportunity to commit to a bold and ambitious future based on transformative strategic investment. We will continue to call on the company to change course, and a clear mandate for industrial action in our ongoing ballot will only strengthen our hand in negotiations.

“Our resolve to oppose Tata’s bad deal for steel – a plan which would be bad for jobs, bad for the environment, bad for national security, and devastating for our communities – has never been stronger.”

Community’s national officer for steel Alun Davies said: “This is an incredibly disappointing day for Tata steelworkers who have been betrayed by a company which owes them so much.

“It is disgraceful that Tata Steel have chosen to pursue a discredited, bargain basement deal over a viable plan for decarbonisation which would protect jobs and preserve the country’s primary steelmaking capacity.

“I know that many of our members will be feeling dejected and anxious today, so it’s vital we stick together to look after one another in these uncertain times.

“It’s also vital that we take a stand together and send a message to Tata that we will not go quietly into the night.

“As someone who has had the privilege of working at Port Talbot and Llanwern, I know first-hand how steel is part of our lifeblood here in South Wales. If the company think that we’ll let them trample over our industry and our communities now, they really don’t know us at all.”

Jo Stevens, shadow Welsh secretary, said: “This is a total gut punch for people in Port Talbot, and the potential economic consequences will reverberate across South Wales for years.

“The Conservative Welsh Secretary has said no one will be left behind if they lose their job. I will be holding him to account on that every step of the way.

“A UK Labour government will invest in our steel industry to make sure the future of UK steel is fuelled by the skills, talent and ambition of Welsh steelworkers.”

The GMB said the meeting was “an unwelcome but not unexpected slap in the face.”

The GMB said one of the blast furnaces at Port Talbot will close by the end of June, and a second in September.

“Discussions will continue on future business commitments on volume and people, including the redundancy package,” said a spokesman.

Jonathan Reynolds, shadow business secretary, said: “It is devastating news Tata Steel are pressing ahead with the Government’s plans to close both blast furnaces in Port Talbot triggering thousands of job losses.

“With other options on the table, and with an uncertain future, Labour urges Tata not make any irreversible decisions about the site.

“Labour has long called for the Government to step in to protect jobs and maintain vital primary steel capabilities in South Wales.

“It’s clear the Government has no plan for steel, for an effective industrial strategy or for our economy.”

Stephen Kinnock, Labour MP for Aberavon, the constituency which includes the Port Talbot steelworks, said: “Tata’s decision to push forward with its shortsighted and reckless plan will have a devastating impact on our local community as it will mean exporting well-paid jobs from Port Talbot to India, despite the country’s steel plants having a far higher carbon footprint.”

Unite general secretary Sharon Graham said: “Tata is an immensely profitable company using our outgoing government’s inadequacies to make easy money and boost its other operations at the expense of UK jobs and the national interest.

“Why else would it be rejecting the promise of £3 billion for UK steel investment from an incoming Labour government and turning its back on a location ideally placed to reap the rewards of a steel market projected to grow tenfold?

“Our current government has utterly failed to stand up to Tata and demand better for Port Talbot and Llanwern’s steel communities and the country.”