A convicted paedophile raped a 10-year-old boy after he was granted bail while facing a string of child sex offences.

David Cullen, formerly of Black-bird Leys, Oxford, attacked the child just days after being released from prison by Judge Julian Hall at Oxford Crown Court, the Oxford Mail can reveal.

Cullen — a former football referee who had been jailed for molesting a 12-year-old boy in 1996 — was remanded in custody after being charged in August 2006 with four sexual assaults against a child and breaching an interim Sexual Off-ences Prevention Order.

But he was then given bail at a hearing in January last year. Last night, child protection campaigners said it was horrific that Cullen — subsequently considered so dangerous he has been given an indeterminate sentence with no fixed date for release — had been freed to abuse again.

The attack came to light this week when Cullen, 48, admitted 28 charges relating to sex offences against five boys, including rape, sexual assault and taking and distributing indecent pictures of children.

The reason why Cullen was bailed was not clear last night.

Amjad Malik, prosecuting, told the hearing this week at Oxford Crown Court: "He committed rape while granted bail by virtue of custody time limits expiring."

These limits set out the maximum amount of time a defendant awaiting trial can spend on remand: The basic rule is if the trial has not started within the time limit, the defendant should be released on bail unless there are good reasons otherwise.

Records held by the court and the Crown Prosecution Service show Cullen was given bail after his barrister applied for his release. Staff were unable to say if custody time limits forced Judge Hall’s hand.

Claude Knights, director of child protection charity Kidscape, said: "You do not get a second chance to get your childhood back.”

NSPCC policy manager Lucy Thorpe added: "We are very concerned about cases of sex offenders released on bail only to commit further crimes against children.”

On Monday, Cullen admitted one charge of indecent assault, two of sexual assault, three of causing or inciting a child to engage in sexual activity, six of raping a child, two of meeting a child following sexual grooming, six of sexual activity with a child, one of attempted sexual activity with a child, four of taking indecent photographs of a child and three of distributing indecent photographs of children.

Court records show he was back in custody by February last year .

Cullen, who is still in prison, will be sentenced next month for the offences he admitted this week.