West Ham United’s financial problems mounted on Tuesday when Alan Curbishley, their former manager, won his claim against the club for constructive dismissal.

A Premier League managers’ arbitration tribunal unanimously upheld Curbishley’s case after he resigned three Barclays Premier League matches into last season over the sales of Anton Ferdinand and George McCartney to Sunderland.

According to the tribunal, the transfers amounted to a fundamental breach of Curbishley’s contract.

The tribunal will now decide on the level of compensation that West Ham — whose debts are thought to be approaching £100 million — will have to pay.

Kevin Keegan was awarded £2 million in damages plus £1.5 million in legal costs after proving constructive dismissal against Newcastle United last month.

“I am obviously delighted with this result,” Curbishley, 51, said. “I very much enjoyed my time at West Ham and never wanted to leave, but on joining the club I insisted that my contract contained a clause confirming that I would have final say on the selection of players to be transferred to and from the club.

“The club completely ignored my contract when selling Anton Ferdinand and when George McCartney was then sold, the club having given me assurances . . . I had no alternative but to resign.

“My authority and integrity were undermined and my position was made untenable. I now wish to put this entire matter behind me.”

Ferdinand was sold for £8 million on August 27, with McCartney following him to the Stadium of Light five days later for £4.5 million. Curbishley left the next day and began a claim for constructive dismissal.

The club filed a counter-claim relating to the cost of employing Gianfranco Zola as Curbishley’s successor and Steve Clarke as his assistant. That was rejected.

Curbishley, a former West Ham midfield player, succeeded Alan Pardew as manager at Upton Park in December 2006, with the club in danger of relegation.

He won his first match in charge, a 1-0 victory over Manchester United, and led them to safety, although it was a close-run thing, with another single-goal defeat of United — this time at Old Trafford — on the final day of the season keeping them up.

He had previously been in charge of Charlton Athletic, twice winning promotion to the Premier League, and his CV means that he will be in demand whenever a job becomes available in the top two divisions.

Curbishley did not consider offers while his action against West Ham was proceeding, but yesterday’s outcome will add to the pressure on managers such as Phil Brown, of Hull City.

“The findings of the tribunal demonstrate the critical importance of respecting contracts, which need to set out the roles and responsibilities of the parties in clear and unequivocal terms,” Richard Bevan, the chief executive of the League Managers Association, said.

Meanwhile, Clarke has defended Hérita Ilunga after Steve Bruce, the Sunderland manager, accused the West Ham left back of “play-acting” during the 2-2 draw on Saturday.

Kenwyne Jones, the Sunderland striker, was sent off after pushing Ilunga to the ground, but Bruce claimed that the defender’s reaction “left a lot to be desired”.

“I find it incredible that a player who was the victim is the person everyone is talking about,” Clarke said. “Tell me what Ilunga did wrong? Someone pushed him in the face.

“He’d just recently recovered from a triple fracture to the jaw — maybe he thought there was a punch coming. It was wrong of Steve Bruce to comment on our players. There was no overreaction; he has to protect himself.”