The boss of one of Britain’s largest trade unions has urged Andy Burnham not to appoint Ed Miliband as his chancellor if he becomes prime minister.

Sharon Graham, the general secretary of Unite, suggested that Mr Miliband might ‘decimate’ Britain’s industry if he is put in charge of the Treasury.

Mr Miliband has been frequently criticised over his Net Zero agenda by Ms Graham, as well as other trade union bosses, in his current role as Energy Secretary.

She has previously branded Mr Miliband’s ban on new oil and gas exploration in the North Sea as an ‘act of self-harm’.

In a major intervention amid Labour’s leadership crisis, Ms Graham has now appealed to Mr Burnham not to promote Mr Miliband if he enters Downing Street.

‘It is no secret that I disagree with Ed on almost every issue relating to a workers’ transition,’ she told The Times.

‘Ed only seems to be interested in one side of the equation, rushing Britain to Net Zero with almost no thought for jobs, skills and national security. 

‘In my view, a Labour chancellor needs a vision for Britain that understands the skills we have, nurtures those skills and sees Britain as an industrial force that can lead in industries, not decimate them.

The Unite chief added: ‘Good investment in British industry is a no-brainer. Anyone who does not get that it matters where things are made and produced should not be chancellor.’

There is a widespread expectation that Mr Burnham will become prime minister in the coming weeks following his thumping win in the Makerfield by-election.

Keir Starmer has vowed to fight any leadership challenge and insisted he will not ‘walk away’, but a large number of Labour MPs are demanding the Prime Minister now swiftly hand power to Mr Burnham.

Mr Miliband is thought to be a leading candidate to be Mr Burnham’s pick as chancellor if he succeeds in ousting Sir Keir, although more recent reports suggest Mr Burnham has cooled on the idea.

It has also been suggested that Mr Burnham could name Wes Streeting, the former health secretary, as a replacement for Rachel Reeves in the Treasury as part of an agreement for Mr Streeting not to stand himself for the leadership.

Unite has traditionally been a major funder of Labour although, earlier this year, the union’s executive council voted to cut its affiliation fee to Labour by 40 per cent, which will cost the party as much as £580,000.

Ms Graham has also repeatedly warned, under Sir Keir’s leadership, that Unite might completely sever ties with Labour.