Tata Steel has abruptly announced it will cease operations of coke ovens at its Port Talbot plant in south Wales, a move condemned by one union as a “massive blow”. The steelmaker, owned by the Indian conglomerate Tata, said it had made the decision after a “deterioration of operational stability”. The move is likely to impact about 200 workers, but the immediate impact remains uncertain. Unions said the announcement had come months earlier than they had anticipated. Alun Davies, Community’s national officer for steel, said: “The early closure of the coke ovens is a massive blow but we knew they have been deteriorating and our No 1 concern is the safety of our members.” The Unite union is calling for strike action over Tata’s proposals. Its regional secretary for Wales, Peter Hughes, said: “Tata needs to halt its plans and wait for Labour’s promised £3bn to reinvigorate the UK’s steel industry. “The time to fight for Port Talbot is now, which is why we are urging Tata’s workers to vote yes to strike action.” In January, Tata Steel said it would shut down its two blast furnaces in Britain by the end of this year, putting close to 3,000 direct jobs at risk, as part of a plan to turn around its loss-making UK steelmaking business by switching to lower carbon electric arc furnaces. Coke ovens are manufacturing plants used to heat coal to make a hard residue called coke, a fuel with high carbon content and few impurities that is a key raw material in steelmaking. The ovens had been due to close by June. Charlotte Brumpton-Childs, a GMB national officer, said: “We were made aware that the coke ovens in Port Talbot were in state of disrepair. It appeared likely they were going to have to close because of this, rather than the decarbonisation strategy. “We were not made aware before the announcement that we had reached a critical state of no return and that the closure was imminent. GMB hoped to reach the end of consultation before any decisions were made.” The Tata Steel chief executive, Rajesh Nair, said: “The performance of the coke ovens has been deteriorating over many months, despite some herculean efforts by the teams there.” Davies added: “Tata know the unions will not accept any compulsory redundancies and we are working to conclude negotiations on an enhanced redundancy and retention package.” Tata said it would increase its imports of coke to compensate for the closure and keep the blast furnaces running for the time being. On confirming the 2,800 jobs cuts linked to the closure of its two blast furnaces in January, Tata said it was not “feasible or affordable” to adopt trade union proposals to continue production at the loss-making plant during a transition to greener, cheaper steelmaking operations. The company said on Monday it was in “advanced stage of consultations” with UK unions on its restructuring plans. After the restructuring, the steelmaker plans to switch to low-carbon electric arc furnaces, a proposal backed by £500m of UK government money. The Port Talbot job cuts have caused considerable political concerns over the impact on the south Wales economy. TV Narendran, the Tata Steel global chief executive, defended the decision in front of MPs in January, saying the steelworks had lost £160m in the previous quarter.