Prominent clergy linked to Oxford’s Christ Church Cathedral are in revolt over a complaint against its dean that they say is “surrounded by secrecy and fuelled by gossip”.

In a row that has convulsed one of the university’s most venerable institutions, the Very Rev Martyn Percy, head of Christ Church as well as dean of the cathedral, has been accused of “immoral, scandalous and disgraceful behaviour”. He has been suspended by the college’s governing body pending a tribunal led by a retired High Court judge later this year.

More than 30 honorary canons headed by Sue Booys, the chair of Oxford diocese house of clergy, wrote last week to Sir Andrew Smith, the former judge, to register concern about the handling of the complaint.

Their letter extolled the “dean’s personal integrity”, and criticised a “sad and cruel delay” before the college’s governing body publicly acknowledged that the unspecified charges against Percy did not relate to safeguarding issues. “The issues relating to this charge seem to be surrounded by secrecy and fuelled by gossip,” it said.

The letter was copied to the Charity Commission, which has oversight of Christ Church as a charitable institution.

According to one of the signatories, the Rev Canon Rosie Harper, the letter “represents the body of the cathedral saying: we’re behind [Percy]”.

Facebook Twitter Pinterest The Very Rev Martyn Percy. Photograph: Greg Blatchford/Rex Shutterstock

A rift between the cathedral and the college’s governing body has significant implications for an academic institution which is uniquely also home to a cathedral. Senior Church of England figures have been supportive of Percy, including the bishop of Oxford, Steven Croft, who said the dean was “widely respected” and that allegations he had been bullied should be investigated.

The college’s governing body wrote last month to alumni to say the dispute did not concern safeguarding, gender bias, access issues or the pay of academic staff: “We are not able to discuss the detailed basis of the complaint except to say that it relates to issues surrounding the dean’s own pay and how it is set.”

Percy – the first dean to be democratically elected by the governing body in 2014 – is believed to earn about £90,000 a year, at the lower end of pay for heads of Oxford colleges. The college’s letter added that “no money raised from alumni is spent on legal fees”. The college is thought to have earmarked about £500,000 for the cost of the dispute and tribunal. Some alumni have written to the college to cancel legacies in protest.

Harper said: “There is an absolutely extraordinary lack of justice here. Nobody really knows what the charges are, but the [college’s] old guard are resisting change and Martyn’s reform agenda.”

Father Robin Gibbons, a Catholic priest and ecumenical canon of Christ Church who also signed the letter, said the four-month delay before clarification from the college that the dispute did not relate to safeguarding issues was “tantamount to calumny by omission”. He added: “Innuendo can destroy reputations – and no institution that takes safeguarding and related concerns seriously should let this happen.”

The issue of Percy’s suspension has been raised in the Commons by the Conservative MP John Howell. “This is a great case of injustice,” he told the Observer. “It’s been very badly handled – even [Anthony] Trollope would find the process to be antiquated,” he said, referring to the 19th-century author whose novels were often concerned with the politics of the church.

Percy, who is said by friends to be deeply distressed over the complaint and to have lost a significant amount of weight, has been forced to hire lawyers for the tribunal. Supporters have raised more than £68,000 for legal fees.

Christ Church declined to comment.