A prison officer at Thamesmead's high security HMP Belmarsh has been found guilty of being the paid mole of a reporter working at the Daily Mirror and News of the World over five years.

Following an Old Bailey trial, Robert Norman, 54, was convicted of committing misconduct in a public office while working at HMP Belmarsh,  which was home to a number of high-profile prisoners.

The court heard he was paid more than £10,000 for 40 tips to reporter Stephen Moyes between April 30 2006 and May 1 2011.

In his defence, Norman, of Milton Street, Swanscombe, denied wrongdoing and told jurors he wanted to highlight problems at the prison in the public interest.

He claimed the case of a Roman Catholic chaplain having affairs with inmates was being "swept under the carpet" by authorities before he told Mr Moyes about it.

The jury in the trial was not told that charges against the journalist had been dropped following a root-and-branch review of Operation Elveden cases by the Crown Prosecution Service.

They took less than a day to find Norman guilty. He will be sentenced by the Common Serjeant of London tomorrow at 9.15am.

Opening the case, prosecutor Julian Christopher QC said Norman was an "extremely experienced" prison officer, having been appointed in 1992.

He was also a member of the Prison Officers' Association, acting as union representative to colleagues.

Norman first phoned the Daily Mirror in 2006 and gave Mr Moyes a story about staff cuts at the prison, for which he was paid £400.

The exclusive story described Belmarsh as a "terror prison" and ran alongside a photograph of one of its most notorious prisoners, "hate preacher" Abu Hamza, the court heard.

As the relationship developed, it became a "two-way affair" and Norman carried on dealing with Mr Moyes when the journalist moved to the NotW.

Mr Christopher said: "Sometimes Robert Norman would approach Stephen Moyes with something he thought would be of interest, at other times Stephen Moyes would approach Robert Norman for inside information about a topic in which he was interested, or for confirmation which he would not be able to get for free from the official channels at the Ministry of Justice press office.

"Effectively, Robert Norman became the journalist's paid mole within HMP Belmarsh."

The court heard that when Norman was arrested in 2013 he maintained he had acted in the public interest as a whistleblower.

But Mr Christopher said: "Whilst there may well be quite a number of stories which would be said to varying degrees to be concerned with issues in the public interest, the prosecution alleges it is plain that this was not the behaviour of a conscience-driven whistleblower, moved by the desire to see change and accountability where otherwise there would be none."

Cheques for the stories were made out to Norman's son Daniel and the money was then transferred into Norman's account, showing he was "worried about the trouble he would get into" if found out, Mr Christopher said.