A judge has cut the sentence of a naval officer who tried to buy an underage girl for sex over the internet after agreeing the conviction had ruined his life.

Lord Justice Rose, one of the nation's most senior judges, said Chief Petty Officer Jeremy Pepper's two-year sentence was too long because the conviction had put an end to his career and had a devastating effect on his marriage.

Cutting six months off the term, the judge said: "He has now been in jail for seven months and it doesn't seem to us that the public interest will be served by him spending much longer in prison."

The decision has provoked outrage among campaigners calling for a zero tolerance approach to child sex offenders.

Pepper, 33, of Upper Drive, Hove, was jailed following a sting operation in the United States. He believed he was exchanging emails with a paedophile who ran "sex tours" in the US but his contact was an American undercover policeman.

The naval officer sent a message confirming he wanted to take part in a paedophile tour and specifically asked for girls aged between 11 and 14 for sex.

Pepper also asked for videos of girls of the same age having sex, and sent three indecent photographs of young girls he had taken.

After Pepper's sentence was cut, Marilyn Hawes, 52, of Billingshurst, who helped get a teacher jailed for molesting two boys, said: "I am still angry and upset and will continue to bang the drum for these people to be jailed.

"I think the judge got it wrong but they always get it wrong. When these people get short sentences the victims don't feel they have been respected for the pain they have gone through."

Carole Easton, ChildLine's chief executive, said: "Short sentences can make victims feel the devastation caused to their lives has not been taken seriously.

"Court sentences must be seen to reflect the damage that has been done to the victims and send out the message that child abusers will be dealt with seriously."

Pepper admitted attempting to incite another to procure a girl under the age of 21 for the purpose of unlawful sexual intercourse and two other sex offences relating to child pornography.

He was jailed for two years at Middlesex Crown Court on September 6 last year.

Pepper first made contact with the undercover officer who was working with British police to catch internet paedophiles in June 2001.

He was arrested on March 19 last year when the police raided his house and seized two computers on which they found 432 indecent images of underage girls.

Lord Justice Rose said: "Having used adult porn for as long as he could remember he came across child porn by accident on the internet and that fueled his fantasies and caused arousal."

He said the conviction had ruined Pepper's career and devastated his marriage.

A spokeswoman from the NSPCC said: "It is important sentences do not send out the wrong messages to sex offenders, that it is all right for them to prey on children. It is never acceptable for an adult to involve a child in sexual activity."