SINGAPORE - An elderly man was asked to keep an eye on a friend's 13-year-old nephew - but ended up sexually abusing him in public.

The 64-year-old - who cannot be named due to a gag order to protect the youngster's identity - was jailed for eight years on Friday (Aug 24) after pleading guilty to two counts of consensual sexual penetration involving the minor, who has a low IQ.

He also admitted to one count of sexual exploitation of a child. Two other charges for similar offences involving the boy were taken into consideration during sentencing.

The court heard that the boy lives with his uncle, aunt and grandmother, as his mother is dead and his father lives elsewhere.

He met the elderly man through his uncle in December 2015.

On March 20, 2016, the boy accompanied his uncle to a coffee shop at Block 516 West Coast Road at around 7pm, where they met the elderly man.

The man was sitting at a table beside the boy when he groped the child's private parts. The boy's uncle later decided to go home after consuming a few glasses of beer.

Deputy Public Prosecutor Asoka Markandu said: "As the victim was familiar with the accused, he (the uncle) told the victim that he could stay with the accused and that the accused would bring him home later."

The location of the teenager's home was not stated in court documents.

The elderly man continued drinking at the coffee shop before leaving with the boy later that evening.

The pair cycled towards Block 714 Clementi West Street 2 and stopped at a nearby pavilion where they performed sexual acts on each other at around 1am the next day.

Two witnesses spotted them and alerted a friend who was doing his national service with the Singapore Police Force.

The off-duty officer then sent a text message to his colleagues about the incident.

More officers arrived at the scene to question the boy and the elderly man before both of them were taken away for further investigations.

For each count of sexually penetrating a minor below 14 years old, offenders can be jailed for up to 20 years and fined or caned. The man cannot be caned, as he is over 50 years old.