A 14-year-old boy who sexually assaulted his five-year-old neighbour must undergo two years of youth rehabilitation.

The boy, who suffers from ADHD, was handed the sentence at Wimbledon Youth Court on Thursday after he was found guilty of two counts of sexual assault following a three day trial in June.

During the trial the court heard how the boy was accused of sexual assault in March last year when he was just 12 after taking the girl to the bathroom while she was in the care of his mother at their Mitcham home.

The boy's mother was close friends with the victim's mother and they live on the same road.

No order was made to ban him from being in contact with the girl as the family were trying to move home.

Defending, Ms Cotcher, said the teenager has a low IQ and ADHD, but his behaviour was improving with medication.

She said: "Coming to court has brought it to mind that there are consequences in his behaviour.

"Both parents understand work needs to be done."

District Judge Ms Bayne said: "It is important for you to understand everybody is trying to help you stay out of trouble.

"I am happy to hear you understand there are consequences to your behaviour."

He was given a youth rehabilitation order for two years, with supervision from a youth offending team.