SINGAPORE - A 64-year-old man who showed pornographic videos to his grandson before sexually assaulting the very young boy on two occasions was sentenced to 12 years' jail on Friday (June 22).

The driver and part-time cleaner cannot be named to protect the identity of his grandson, who was seven to eight years old when he was abused in the family's four-room flat between 2015 and 2016.

The man pleaded guilty in February this year to one charge of aggravated sexual assault by penetration and one charge of molestation. Three other charges - one of molestation and two of showing pornographic videos - were taken into consideration.

The court heard that on one afternoon in early 2015, the man called the boy to his room and fondled him. When the family's domestic helper called for the boy, the man panicked.

He told the boy to get dressed and warned him not to tell anyone about what had happened, saying that it would "create problems" with his parents.

In December that same year, the man was sent to a drug rehabilitation centre. He was allowed to return to his family in September 2016.

More than a week after he returned home, on Sept 28, the man sexually violated the boy in his room while they were alone at home. He again warned the boy not to tell anyone.

The incidents came to light a month later, on Oct 22, when the boy's mother reminded him to go to bed early as the family was planning an outing the next day. She told her son that if he could not wake up on time, he would have to stay at home with his grandfather. This prompted the boy to tell her about the sexual abuse.

Shocked, the woman confronted her father, who admitted his wrongdoing. A police report was made the next day.

On Friday, the prosecution sought at least 12 years' jail for the man, who cannot be caned as he is more than 50 years old.

Deputy Public Prosecutor Winston Man argued that the case "features intrinsic elements of depravity" and underscored the need for deterrence.

He said the accused had "flagrantly abused the trust of the victim and his parents" and had morally corrupted his own grandson by showing him pornographic material as a precursor to sexual acts.

Defence counsel Derek Kang asked for a sentence of not more than 10 years' jail, arguing that his client had shown remorse by cooperating during police investigations and pleaded guilty to save the court's time.