An unemployed man who assaulted his girlfriend and left her with rib fractures and bruises was jailed for 21 months and ordered to be given three strokes of the cane on Thursday.

Lim Cheng Hian, 34, had been drinking when he subjected his then girlfriend to a two-hour ordeal, slapping, punching, kicking and even cutting her thigh with a knife. He pleaded guilty to three of five charges.

A district court heard that the victim, Ms Chin Yin Choo, 35, moved into Lim's flat in Sengkang in April 2012 after they dated for about two months.

Sometime between June and July that year, the couple were walking back from a mall when Lim bought some alcohol from Cheers minimart.

He started drinking at a void deck and accused the victim of having an affair behind his back. She was afraid and did not want to go back to the flat, but eventually did so when Lim promised that he would not beat her.

When they reached the flat, he again asked her whether she was having an affair.

When the victim denied this, he dragged her to the bedroom and started slapping, punching, strangling and kicking the victim. He also pushed her head against the wall, causing the back of her head to bleed. The victim then passed out.

When she came to, Lim was still drinking. He approached her again and began kicking her repeatedly on her stomach area. He then left the room to drink.

He returned shortly and used a Swiss Army knife to cut her on the leg.

He did not take her to see a doctor although she had pain in the ribs and the back of her head. Her entire body was bruised and she was bleeding from the nose and lips. He woke up at 10am and gave her some ointment to apply.

Ms Chin saw a doctor on July 10 that year and was found to have two broken ribs and scars over her scalp.

District Judge Eugene Teo noted from Lim's psychiatric report that he had a problem with alcohol dependence and advised him to address it accordingly upon his release from prison.