Britain’s biggest police force has been accused of a “betrayal of the public” and continuing to “lack candour” in its statements over the unsolved murder of private investigator Daniel Morgan.

The Metropolitan Police were accused of institutional corruption by an independent panel over the 1987 killing, which has remained unsolved despite at least four police investigations and an inquest.

Father-of-two Mr Morgan was murdered with an axe in the car park of the Golden Lion pub in Sydenham, south-east London, in March that year, and his killer has never been brought to justice.

On Wednesday, chairwoman of the panel Baroness Nuala O’Loan told the London Assembly Police and Crime Committee that public statements made by senior officers following the panel’s report were “most disappointing”.

Met Commissioner Dame Cressida Dick, Assistant Commissioner Nick Ephgrave and Deputy Commissioner Sir Stephen House were all defiant and refused to accept the finding of institutional corruption.

The report said: “Concealing or denying failings, for the sake of the organisation’s public image, is dishonesty on the part of the organisation for reputational benefit and constitutes a form of institutional corruption.”

Baroness O’Loan told the committee: “We have found the Met to be institutionally corrupt and the responses by senior officers to the report have been most disappointing.

“The public statements which we have heard from the Commissioner, Deputy Commissioner (and) Assistant Commissioner in the days following the publication illustrate exactly the problem we have been describing.”

The peer said senior officers “have continued to lack candour” in their public statements even after the publication of the damning report.

Baroness O’Loan said “incompetence and corrupt acts” had hampered all the investigations into Mr Morgan’s death.

“The Met, as an organisation, has not responded honestly to the public and to the family about the serious failures including incompetence and corrupt acts in the murder investigations over the past 34 years,” she said.

“The Metropolitan Police has placed concern for its reputation above the public interest.

“There has been dishonesty for the benefit of the reputation of the organisation and that is institutional corruption, and the statements made on behalf of the Met have continued to lack candour, even after the publication of our report when they referred specifically only to the failings in the first investigation.”

She added: “This is a betrayal of the family, and it’s also a betrayal of the public and of good, honest officers. And it will diminish trust.”

Later, the committee heard from Dame Cressida who repeated her rejection of the accusation of institutional corruption.

While she said it was “a very significant report” that they take “extremely seriously”, she said the claim was “bordering on offensive”.

She said: “In terms of institutional corruption that’s not the Met I see today.”

Dame Cressida added: “I don’t accept that’s the Met I know, and I find bordering on offensive I suppose, the suggestion that we keep things quiet to protect our reputation currently.

“That’s not the Met I lead, that’s not the Met I see.

“However, there may be occasions when we look like that, when we are perceived to be. I’m absolutely determined that we up our game on our openness and our transparency.”

The report criticised the Met for treating panel members like litigants and the Commissioner for initially refusing them access to an internal database known as HOLMES.

Dame Cressida refused to answer the committee’s questions about her relationship with the panel because the Mayor’s Office for Policing and Crime (MOPAC) is currently considering whether there are any “possible issues of conduct”.

A MOPAC spokesman said: “In line with its statutory responsibility, the Mayor’s Office for Policing and Crime is considering any possible issues of conduct in relation to the Commissioner of the Metropolitan Police arising from the Daniel Morgan Independent Panel report.”

Dame Cressida said she would answer questions on the topic at a later date.