Port Talbot is owned by Tata Steel, which will also invest £725m in emissions-cutting efforts, but as many as 3,000 job losses are expected as part of the restructuring deal.

Unions representing workers at the plant complained they had been shut out of negotiations.

Charlotte Brumpton-Childs, GMB national officer, said: “Government intervention in the steel industry is long overdue, but imposing a programme without proper worker consultation is unacceptable.

“GMB has urged ministers and Tata Steel to have a longer-term view on the decarbonisation of steel.

“It is not a just transition if thousands of jobs are sacrificed in the name of short-term environmental gains.”

The carbon reduction plan will see a new electric arc furnace being installed at Port Talbot, which is currently the UK’s largest single carbon-emitting facility. This would replace the existing coal-powered blast furnaces – which are nearing the end of their effective life – and reduce the...