Stevens was sentenced to eight months in prison

Stevens, 43, gave a false alibi when he was accused of downloading child porn on the internet, a charge which was later dropped for lack of evidence.

He was jailed at the Old Bailey for eight months on Friday. Stevens had been a family liaison officer for the family of murder victim Jessica Chapman.

Stevens was suspended from the police in September 2002 but has been receiving full pay ever since.

Anger and disappointment

On Tuesday officers from the Cambridgeshire force's standards department visited him in prison to serve him with a disciplinary notice and a tribunal was held on Wednesday.

Stevens did not attend but was sacked with immediate effect on the basis that he had been convicted of a criminal offence and could therefore no longer serve as a police officer.

Assistant Chief Constable John Feavyour said the case had cast a shadow over the force.

"I am extremely angry and disappointed in former Detective Constable Stevens' behaviour and I know this feeling is shared by honest, hardworking colleagues who feel it has reflected badly on the force as a whole.

"Having been convicted by a criminal court of an offence that strikes at the core of integrity and honesty, I know that colleagues and the public will consider it appropriate that he has been dismissed," he added.

Operation Ore

Stevens was arrested at his Cambridgeshire home in September 2002, after his name came up in Operation Ore, a UK-wide trawl of internet paedophiles.

He was charged after indecent images of children were found on his laptop, but the case was later dropped for lack of evidence.

But police found he had given them a fake alibi in relation to the computer offences.

He had claimed he was nowhere near his computer when child porn was downloaded on to it.

Stevens said he was more than 100 miles away staying at the home of a close friend, Louise Austin, with whom he denies having a sexual relationship.

Miss Austin, 32, an executive case officer for the Crown Prosecution Service, backed up the fake alibi and was also convicted of conspiring to pervert the course of justice at the Old Bailey last Friday.