A pair of brothers ganged up to assault their mother's former boyfriend, and one of them helped to seize the man's mobile phones for his mother to check if he was in contact with other women.

Yesterday, Ng Shiuh Shao, 24, was sentenced to two years' jail, and his brother Shiuh Leong, 23, nine months, for assaulting Malaysian national Tey Meng Seng.

The court heard that Mr Tey, 42, then a dishwasher, got to know 45-year-old Cindy Lim through Facebook and they developed a romantic relationship which ended in December 2015. Mr Tey's subsequent relationship with another woman, Ms Leong Choi Kuen, 47, ended some time before the assault on March 28, 2016.

Deputy Public Prosecutor Yang Ziliang said the two women decided to confront Mr Tey that day about his relationships with them and "financial issues". It is not known how the women got to know each other.

Madam Lim called her older son and told him she was going to meet the victim and "needed his help".

Ng was with his younger brother and a friend, known only as Ashrin. The trio took a taxi to the Shepherds Drive rental unit where Mr Tey was living, to meet up with the two women.

The three men waited for Mr Tey and rushed towards him when he came home. They pushed him into the compound and punched him, shouting Hokkien vulgarities.

The trio "shared a common intention to cause hurt to the victim", said DPP Yang.

Mr Tey suffered blows to his head, face, chest and arms in an attack that lasted five minutes. He was also struck with a stool. The elder Ng then took a knife from the victim's kitchen and asked him to hand over his two mobile phones.

The women checked the phones to see if he was in contact with other women. The group also photographed his personal documents.

Mr Tey later found his phones had been reset. He made a police report two days later, on March 30. Medical reports showed he had suffered several injuries including bruises and a fracture on his right wrist.

In January, Ng Shiuh Shao pleaded guilty to one count of voluntarily causing grievous hurt while his brother Shiuh Leong did the same to one count of voluntarily causing hurt. Their accomplice Ashrin is still at large.