It was announced in January that the Croat had been provisionally suspended after allegedly breaching the WTA’s Code of Conduct.

On Tuesday, the WTA – the governing body of women’s tennis – confirmed Vukov’s ban had been upheld.

The 37-year-old has denied any wrongdoing and Rybakina has said she was never mistreated by him.

Confirming the conclusion of the investigation to BBC Sport, the WTA added: “Following this process, the suspension remains in place.

“To protect the confidentiality and integrity of the investigation and its findings, the WTA will not provide further details. We remain committed to ensuring that all matters are handled in a fair and objective manner in accordance with the WTA Code of Conduct.”

It would not specify how long Vukov will be banned for and it is not known which part of the WTA’s code he has broken.

Vukov can appeal against the decision.

The decision means Rybakina will not be able to bring Vukov back on to her team – something she hoped to do at the start of the year.

Concerns have been raised over the past few seasons by some, including coach and commentator Pam Shriver, about Vukov’s behaviour towards 25-year-old Rybakina.

The manner in which he spoke to her on and off court at tournaments has come under scrutiny.

Kazakhstan’s Rybakina, who won the Wimbledon title in 2022, said at last month’s Australian Open she has never made “any complaints” about Vukov, adding: “I don’t agree with a lot of things the WTA do in the sense of my relationship with Stefano”.

Rybakina worked with Vukov from being a teenager and he helped her claim her first Grand Slam at Wimbledon, but the partnership ended before last year’s US Open.

She announced in January she wanted Vukov to rejoin her team but the provisional suspension meant he did not receive accreditation for the opening Grand Slam of the season.

Rybakina, speaking before the Dubai International began on Sunday, said she was in contact, external with Vukov and he was helping her with “a lot of things, on the court, outside of the court”.