The national lottery operator Camelot is launching a high court challenge to the gambling regulator’s decision to hand over the operation of the draw to a rival after 28 years, accusing the regulator of getting the decision “badly wrong”.

In a statement, Camelot’s chief executive, Nigel Railton, said: “We are launching a legal challenge today in our capacity as an applicant for the fourth [national lottery] licence because we firmly believe that the Gambling Commission has got this decision badly wrong.”

The Gambling Commission said it “regrets” Camelot’s decision and expects the high court to find that it ran a “fair and robust” process.

Allwyn, a lottery operator owned by the Czech billionaire Karel Komárek, is in line to take over from Camelot in 2024, after beating the incumbent in a four-way battle that also included Sisal, owned by the Paddy Power parent, Flutter, and the media tycoon Richard Desmond.

“When we received the result, we were shocked by aspects of the decision,” Railton said.

“Despite lengthy correspondence, the commission has failed to provide a satisfactory response. We are therefore left with no choice but to ask the court to establish what happened.

“Irrespective of Camelot’s dual roles as current operator and applicant for the next national lottery licence, the competition is one of the largest UK government-sponsored procurements and the process deserves independent scrutiny.

“Separately, more than 1,000 Camelot employees work tirelessly to successfully operate the national lottery under the current licence and, at the very least, they are owed a proper explanation.”

The Gambling Commission said it was confident that Camelot’s legal challenge would fail.

“We regret Camelot’s decision to bring legal proceedings following the outcome of a highly successful competition for the fourth national lottery licence,” a spokesperson said.

“The competition and our evaluation have been carried out fairly and lawfully in accordance with our statutory duties, and we are confident that a court would come to that conclusion.

“We have taken every step possible to ensure a level playing field for all interested parties, to enable us to appoint a licensee who will engage and protect players, run the national lottery with integrity and ensure the national lottery continues to support good causes and their contribution to society.

“Our priority is to continue to work to implement our decision and ensure a seamless and timely transition to the next licence, for the benefit of participants and good causes.

“These proceedings will not help that but we trust that Camelot will honour its obligations as the current licensee to cooperate in that transition, and we will continue to use the tools available to us to facilitate that process.”