UNITE general secretary Sharon Graham warned today that she would “keep [Labour’s] feet to the fire” over its manifesto pledge to invest billions to save Britain’s struggling steel industry.

She was speaking on the BBC’s Sunday With Laura Kuenssberg after Business Secretary Jonathan Reynolds said “job guarantees” would be part of the negotiations between the government and steel giant Tata about its Port Talbot site in South Wales, where 2,800 jobs are under threat.

Ms Graham said Labour would have to borrow to invest in British industry — “we do not have time to wait for growth.”

She said: “There is no doubt that Labour coming in and the intent of what they want to do is a good thing. I am glad we have a Labour government.

“But I am the leader of a trade union and my focus is on jobs, pay and conditions for workers.

“The problem we have is that when investment is spoken about in Britain, there are never job guarantees attached. 

“The devil will be in the detail and I am going to keep an eagle eye on what that detail means.”

Mr Reynolds said on the BBC show: “There is a better deal available for Port Talbot and the steel industry as a whole.

“I do want things in exchange for money — we’ll co-invest with the private sector around jobs and technology.”

Ms Graham added: “I am going to be seen as either a critical friend or a pain in the proverbial.”

The Labour manifesto has committed to provide £2.5 billion to “rebuild our steel industry,” with Mr Reynolds noting this was on top of the £500 million committed by the previous government.