The owner of Royal Mail has accepted a £3.57 billion ($4.6 billion) takeover bid from Czech billionaire Daniel Křetínský, paving the way for the sale of one of Britain’s oldest and most iconic institutions to a foreign owner for the first time.

International Distribution Services, which owns the loss-making postal service, said Wednesday that it had accepted a £3.70-per-share ($4.69) takeover offer from Křetínský’s EP Group.

The deal has consequences for thousands of workers and has sparked anxiety about the future of a key piece of national infrastructure, which delivers a vital public service.

EP Group has made several commitments to address these concerns, including upholding Royal Mail’s “universal service obligation,” which requires it to deliver letters six days a week everywhere in the United Kingdom for the same flat fee.

It has also promised to maintain employee benefits and pensions, and keep Royal Mail’s headquarters and tax base in the UK.

“The EP group has the utmost respect for Royal Mail’s history and tradition, and I know that owning this business will come with enormous responsibility — not just to the employees but to the citizens who rely on its services every day,” Křetínský said in a statement.

He added that IDS has the potential “to become one of the largest postal logistics groups in Europe,” but that its “market is evolving quickly” and it must modernize to keep up with rival delivery services. Křetínský’s Vesa Equity Investment, a private equity firm, is already the largest shareholder in IDS, with a 27.6% stake.

Politically sensitive

The deal follows a torrid few years for Royal Mail, which was privatized in 2013. It has suffered a sharp drop in demand for its services and recorded a loss of £348 million ($445 million) for the year that ended on March 31 — a slightly better result than the previous year when it lost £419 million ($536 million).

“The IDS Board believes that the offer from EP is fair and reasonable given that there are uncertainties ahead and allows investors to realise value at a significant premium,” IDS chairman Keith Williams said in the statement.

Not everyone is convinced, however.

Dave Ward, general secretary of the Communication Workers Union, which represents about 110,000 Royal Mail workers, said the takeover was “a direct result of a failed and ideological privatisation over a decade ago mixed with the blatant mismanagement of the company in recent years.”

Workers wanted further commitments from EP Group on the future of the company, he said.

“We do welcome some of the commitments that have been made but the reality is postal workers across the UK have lost all faith in the senior management of Royal Mail and the service has been deliberately run down,” he added in a statement.

Křetínský’s move comes at a sensitive moment politically as the United Kingdom gears up for a general election on July 4. The proposed takeover will be subject to a national security review, possibly by a new government. Opinion polls suggest the Labour Party will win its first election since 2005 and replace the incumbent Conservative administration.

Labour has already taken a keen interest in the deal.

“Royal Mail is as British as it gets, and Labour will take the necessary steps to safeguard its undeniable identity and place in public life,” Jonathan Reynolds, the party’s business spokesperson, wrote in a letter to Křetínský earlier this month.

A low-profile Czech national, Křetínský made his fortune through a sprawling empire of European energy companies, retailers and football clubs. He is worth an estimated $7.7 billion, according to the Bloomberg Billionaires Index, and owns a 27% stake in West Ham United Football Club.