A teenage boy who sexually abused his little  sister while babysitting had been watching online porn, a court has  heard.

The 17-year-old repeatedly seriously abused  the four-year-old child until the victim eventually told their mother what he  had been doing.

She reported her son to the police and when  interviewed the boy, who cannot be identified for legal reasons, admitted his behaviour had been ‘disgusting and loathsome’.

The teenager was today sentenced to three and a half  years detention at Liverpool Crown Court (pictured) after pleading guilty to  attempted rape and five offences of sexual assault

Sentencing the youth, who is now 18, to three  and a half years detention Judge Mark Brown described him as an intelligent  young man who had known what he was doing was wrong.

He said: ‘I am told you had been watching  pornographic films.

‘It is clear from what you said to police  that you knew you had abused your sister and you appreciated that what you had  done to her was not only disgusting but also loathsome but despite that  knowledge you carried on and continued to treat her in that way.’

He said that the youth had treated her in a  ‘most appalling and dreadful fashion’ because he had been sexually  aroused.

The defendant had pleaded guilty to attempted  rape and five offences of sexual assault.

Gerald Baxter, prosecuting, told Liverpool  Crown Court today that the offences took place over a four month period last  year and the offences were specimen charges.

The court heard the teenager had been watching  pornographic films (file picture posed by model)

Judge Brown said that fortunately the victim  did not seem to have been adversely affected by the abuse and had ‘simply  shrugged it off and was getting on with her life’.

He said that the boy, who had been bullied at  school, largely because of his weight, was socially isolated.

Following the death of his father he had  become even less outgoing and when he was 16 was convicted of indecent  exposure.

The judge said he accepted he was genuinely  remorseful and his mother and family are continuing to support him.

He ordered him to sign the Sex Offenders  Register for life, disqualified him from working with children and imposed an  indefinite Sexual Offences Prevention Order preventing unsupervised contact with  children.

Julian Linskill, defending, said that there  had been an element of sexual experimentation involved in the offences.

He urged the judge not to send the youth to custody and instead put him on a sex offender rehabilitation course.

Read more: DailyMail