Massimo Cellino has been barred as Leeds United owner by the Football League and will not be permitted to exercise control at the Championship club for almost three months, after the Italian’s appeal against his disqualification was rejected.

Cellino was initially disqualified in December when the League ruled a first-grade conviction for tax evasion on a yacht in Sardinia was a “dishonest offence” and that he was therefore in breach of the organisation’s owners’ and directors’ test. The 58-year-old had his appeal against the decision rejected by a professional conduct committee including the League chairman, Greg Clarke, on Monday.

It means Cellino, whose company Eleonora Sport purchased a 75% stake in Leeds last April, will have to step down as a club director by Wednesday and show that he is not acting as a “relevant person” until 10 April, a period of 79 days. His first-grade conviction for tax evasion on his yacht, the Nelie, becomes spent in the British legal system on 28 March – 12 months after the original ruling in Italy – following a recent change to the Rehabilitation of Offenders’ Act.

Leeds’ chief operating officer, Matthew Child, confirmed the club would be as compliant “as they needed to be” with the ruling but could not comment on who would be running the club in Cellino’s absence. “I can’t at this stage,” Child told BBC Radio Leeds. “We’ve a few more discussions to have. There are lots of priorities at the moment and that’s one of them, but probably not the top one at this moment in time, very close, but not the top. We need to sit down with the president, the Italian counsel, the British counsel, myself and another couple of guys. It’s very early days for us yet. As with anything to do with Leeds United, it’s never straightforward is it?”

“We are surprised and really disappointed. We will continue to take legal advice and we are working round the clock, as we have been for a period of time, to see what our options are because this is uncharted territory for all of us.”

He added: “We don’t know what the implications are. We’re going to be as compliant as we need to be. We’re in constant discussions with the Football League and our own board and senior management team, we’re not sure.”

Tim Kerr, the independent QC who chaired the professional conduct committee, dismissed the legal arguments made by Cellino’s lawyers, and one from the club director Andrew Umbers that claimed there was “a real likelihood of insolvency” should Cellino be disqualified.

The League ruled that judge Sandra Lepore’s full written judgment of the tax case clearly showed that the Italian had acted dishonestly when failing to pay import tax. As revealed by the Guardian last September, Lepore described Cellino’s “elusive intent” and a “bogus corporate scheme” relating to the case in 2012, when he failed to pay nearly €390,000 (£300,000) import duty on the yacht.

A League spokesman said: “The Football League’s sole objective throughout this process has been to ensure that our regulations, as democratically approved by our member clubs, are complied with. These regulations uphold principles relating to club ownership that are widely recognised to be in the interests of the game and have the support of the other football authorities, the government and football supporters generally.” among supporters, with the team struggling in the Championship this season and perilously close to the relegation zone, sacking three managers since his arrival.Cellino has been heavily involved in all club matters at Leeds since he first bought the club last year. He has divided opinion

It is unclear who will run the club in his absence. Cellino has two sons on the board at Leeds, as well as his American financial adviser, Daniel Arty, although during the PCC hearing a lawyer for the League stated “family members would not necessarily have to divest themselves of their stakes in the club”. The former owners and investment bank, Gulf Finance House Capital, remain 25% shareholders in the club, while Child added: “Massimo feels like he has been invited to a party and, when he has shown up, he hasn’t been allowed in.”

Cellino has two more import tax cases to be heard in Italy this year, on a Range Rover and a second yacht called Lucky 23, while Leeds are under a transfer embargo for the January window after breaching financial fair play regulations when owned by GFHC.

A statement from the League added: “A further misconduct charge against Mr Cellino and the club for failing to supply the Italian court judgment to the Football League when it first became available will be heard by a Football Disciplinary Commission in line with League regulations in due course.”