A 70-year-old man who sexually assaulted a boy with autism has been jailed for six years.

Castlebar Circuit Criminal Court heard the 11-year-old boy was approached by the man in April 2015 and enticed into a laneway with an offer of €25.

The accused touched the boy and kissed him on the mouth.

The child’s mother became suspicious when he arrived home with a pizza he bought with the money the man gave to him.

She informed gardaí when her son told her what had happened.

The accused was arrested after the assault and has been in custody since then.

He has previously been convicted and jailed in the UK for sexual offences.

In a victim impact statement read to the court today, the boy's mother said her son had suffered sleep disturbance and weight loss since the incident.

He has also been aggressive and has exhibited sexual behavior and had been teased and bullied following the abuse.

Judge Rory McCabe described the defendant as "predatory" and "dangerous".

He said children were unsafe in his presence and he expressed concern he would re-offend if he was not jailed.

The man's previous convictions date back to 1975 when he was first convicted in the UK for indecent exposure.

He moved to the west of Ireland with his wife ten years ago.

The time he has already spent in prison will be factored into his six-year jail sentence.