THE leak of allegations that police found pornographic images on the work computer of Cabinet minister Damian Green should never have happened, the chief inspector of constabulary has said.

Amid the growing political furore over the way two retired officers passed details to the media, Sir Thomas Winsor said police had an "enduring" duty of confidentiality, even after they had left the service.

In a statement, he said if a serving officer had breached that duty they would face disciplinary action potentially leading to dismissal and, in certain circumstances, criminal charges.

"The special powers which citizens confer on police officers are inseparable from the obligations of special trust placed in police officers to enable them to do their duty," Winsor said.

"The obligation of confidentiality, and the duty not to break trust, is an enduring one. It does not end when a police officer retires."

On Friday, ex-Scotland Yard detective Neil Lewis told the BBC he was "shocked" at the volume of material found in a 2008 police raid on Green's Westminster office and had "no doubt whatsoever" it had been amassed by the Tory MP.

The allegations echoed claims made by former Metropolitan Police assistant commissioner Bob Quick, who went public last month with his account of the material discovered during an investigation into Home Office leaks.

The claims by the two ex-officers added to the pressure on embattled Green – Theresa's May's closest political ally and effective deputy prime minister.

The minister, who is the subject of a Cabinet Office inquiry into alleged inappropriate behaviour towards a young female activist, has vehemently denied looking at or downloading porn on the work computer.

As Tory MPs rallied round in support, former attorney general Dominic Grieve said the leaks had "the smack of the police state".

In his statement, Winsor said that if the police could not be trusted with confidential information, public confidence would be damaged.

"The public need to know that when information about their private lives comes into the possession of the police, and that information is irrelevant to the work of the police, its confidential and private nature will be respected in perpetuity," he said.

"If public confidence in this respect is damaged, and people do not believe they can trust the police in such circumstances, great harm may be done to the relationship between the police and the citizen, and the efficiency and effectiveness of the police will be impaired.

"Such violations may have a chilling effect on the willingness of victims and witnesses to co-operate with the police, and that will be at the expense of public safety and justice. They should never occur."

The Metropolitan Police has already said it is launching its own inquiry about how information gathered during an investigation was made public.

Lewis has said that he was involved in analysing the then-opposition immigration spokesman's computer during the 2008 investigation into Home Office leaks.

He stressed that none of the images he saw were "extreme", but said analysis of the computer suggested they had been viewed "extensively" over a three-month period, sometimes for hours at a time.

On Friday, Green said: "I have maintained all along and I still maintain – it is the truth – that I did not download or look at pornography on my computer, but obviously while the investigation is going on I can't say any more."