Connor Larbalestier tried to persuade girls as young as 13 to send him nude pictures of themselves and asked one girl if she would sleep with him for £500.

Autistic Larbalestier was aged 18 or 19 at the time and used Facebook to contact girls who he had never met because he was immature and naive, Exeter Crown Court was told.

He had previously had a sexual relationship with a 14-year-old girl when he was 17 and police found two indecent pictures of her on his phone when he was arrested.

Larbalestier carried on using Facebook to contact girls even after he had been interviewed by the police but he always denied ever trying to arrange a face to face meeting with them.

Larbalestier, aged 20, of Bladon Close, Newton Abbot, admitted two offences of sexual activity with a child, three of inciting children aged 12, 13, and 14, to engage in sexual activity, and two of possessing indecent images.

He was jailed for 18 months in a young offenders’ institution by Judge Geoffrey Mercer, QC, who also imposed a Sexual Harm Prevention Order which will restrict Larbalestier’s use of social media after his release.

He told him:"Cases of this sort are sadly becoming far too common. These are serious matters which are a cause for concern

"An aggravating feature is that in some of these cases you were on bail but continued this activity for reasons I find hard to understand.

"You knew the age of the girls you contacted and initiated totally unsuitable conversations with them about sexual matters."

Mr Richard Crabb, prosecuting, said the Facebook offences took place last year when the defendant contacted three girls and started sexualised conversations.

They culminated in him asking one girl if she would sleep with him for £500 and offering a 13-year-old money and a mobile phone if she performed online sex acts for him.

Mr Joss Ticehurst, said Larbalestier was isolated by his autism and the offences arose from his immaturity and naivety.