The strike action, described by Unite as the first strikes by British steel workers in 40 years, will take place at Tata’s Port Talbot and Llanwern sites in Wales.

A spokesman for Tata Steel said the company was disappointed by Unite’s decision, adding that the steel-making assets were operationally unstable and causing losses of £1 million a day.

“If the safety and stability of our operations are put at risk by this action, we will be forced to accelerate those closure plans,” the spokesman added.

The closures were announced in January as part of the Indian company’s plan to turn around its loss-making UK business by switching to lower carbon electric arc furnaces, a proposal backed by £500 million of government money.

“Tata’s workers are not just fighting for their jobs – they are fighting for the future of their communities and the future of steel in Wales,” Unite’s general secretary Sharon Graham said.

Tata Steel employs more than 8,000 people in the UK. The company said in January about 2,500 jobs of the total being cut were likely to go over the next 18 months.