While his tenant was sleeping, a father of three children crept into his bedroom and performed oral sex on him.

About 10 minutes later, the tenant woke up kicking and screaming.

Former project engineer Waduge Buddhika Upashantha Fernando, 38, yesterday pleaded guilty to non-consensual sexual penetration in his Kim Keat Avenue flat in Toa Payoh.

The tenant, a 28-year-old Malaysian cook, had lived with Fernando, a Singaporean originally from Sri Lanka, and his family for about four months when the offence happened.

He had little interaction with the family as he usually left the flat by 9am and returned at 11pm.

On Nov 10 last year, he fell asleep at about 1am, said Deputy Public Prosecutor Marshall Lim.

When Fernando got home at around 3am, he felt an urge to have sex with another man.

The tenant woke up about 10 minutes later and saw Fernando committing the offence.

DPP Lim said: "The victim yelled and kicked at the accused. The accused... then left the flat immediately. The victim was shocked and did not know how to react."

The cook alerted the police about an hour later.

In urging District Judge Kessler Soh to sentence Fernando to at least eight years' jail with four strokes of the cane, DPP Lim said: "When penetrative sexual assault involves landlords and tenants who share the same premises, it will undoubtedly cause grave public disquiet."

Fernando's lawyer, Mr Amolat Singh, pleaded for a five-year jail sentence for his client.

Mr Singh told Judge Soh: "He did not use any violence or any force or any stupefying drug to overcome the victim's resistance or to obliterate his memory.

"There was no moral corruption nor is there any evidence that the victim suffered grave psychological or emotional trauma."

Fernando, who is out on $25,000 bail, will be back in court on July 17.