Michael Barrett, 20, of Greystoke Avenue, Southmead, Bristol, was given a two-year conditional discharge at the city's crown court on Monday.

The Attorney General has asked to see the case papers after complaints from a child safety campaign group.

The group condemned Judge Michael Roach who, when sentencing Barrett, said the girl had been a "willing participant".

If the Attorney General considers the sentence to be "unduly lenient", the case could be referred to the Court of Appeal.

Guilty plea

A spokeswoman said the Attorney General had received a complaint from a group called Phoenix Survivors.

This is an internet-based organisation set up for and by the victims of child abuse.

"We have been asked to consider whether the sentence is unduly lenient and we will be doing so," the Attorney General's spokeswoman said.

He has 28 days from the sentence being imposed to make any referral to the Court of Appeal.

Barrett pleaded guilty to having unlawful sex on two occasions with the 12-year-old at her home in Greater Manchester.

He had befriended the girl on the internet and then met her at a concert in London.

Under laws brought in May this year, sex with a child under 13 is classified as rape and is punishable with a life sentence.

We want more than an appeal against the sentence, we want an apology Shy Keenan, founder of Phoenix Survivors

But the act is not retrospective which meant Barrett was sentenced for unlawful sexual intercourse, although that too can carry a life sentence when the victim is under 13.

Barrett was ordered to sign on the Sex Offender Register for two years.

Shy Keenan, founder of Essex-based Phoenix Survivors, said the group was angered both by the sentence and the judge's comments.

She said it sent the wrong message to potential child abusers and to children who may want to report abuse.

"We want more than an appeal against the sentence, we want an apology," Ms Keenan said.

In 2002, the Attorney General referred 134 cases to the Court of Appeal.

It decided the sentences in 115 of these were unduly lenient and increased the sentences in 91 cases.