The Czech billionaire vying to buy Royal Mail has pledged not to cut any jobs if his takeover bid is successful.

Daniel Kretinsky, known as the “Czech sphinx”, has made private assurances that there will be no compulsory redundancies as a result of his swoop on the 500-year-old postal service.

He has also vowed not to break up Royal Mail’s parent company and to maintain its investment grade credit rating, according to sources familiar with the tycoon’s thinking.

The promises come as Mr Kretinsky’s EP Group prepares to make a fresh bid for Royal Mail ahead of a deadline of May 15 under City takeover rules.

His initial £3.1bn offer for parent company International Distributions Services (IDS) was rebuffed last month, with the board branding it “opportunistic”.

The approach by Mr Kretinsky, who is also an investor in West Ham Football Club and Sainsbury’s, is likely to prove controversial given the sensitive nature of the postal service.

Sir Vince Cable, who oversaw the privatisation of Royal Mail in 2013, has called on ministers to carry out a fit and proper person test on Mr Kretinsky.

The tycoon was previously subject to a national security investigation when he increased his stake in the company above 25pc in 2022, though this was ultimately approved.

Chuka Umunna, the former shadow business secretary who is now a senior banker at JP Morgan, is among a team of advisers lobbying the Labour Party on behalf of Mr Kretinsky.

The pledge not to cut jobs will be seen as an olive branch to the Communication Workers Union (CWU), which has voiced its opposition to the takeover.

Dave Ward, CWU general secretary, has asked for a meeting with business secretary Kemi Badenoch amid concerns Royal Mail had been “further destabilised” by the takeover bid.