SINGAPORE - A man came up with a plan to rob prostitutes to earn some easy money and his two friends agreed to help him.

They found a target, assaulted her in her home and told her they were police officers, with one of them flashing his Institute of Technical Education (ITE) identification card. They then robbed the victim and stole from her housemate.

On Wednesday (Dec 27), Rigel Douglas Wong, 27, who hatched the plan, was sentenced to 3½ years in jail and 12 strokes of the cane for robbing a masseuse of cash and two mobile phones.

He pleaded guilty to robbing Ms Xiao Meirong, 35, of $1,050 worth of property with Hideyoshi Tanaka, 29, and Gabriel Foo Junxian, 22, and punching her face and pushing her head several times on April 1, 2015.

He also admitted to stealing an iPad mini and two mobile phones totalling $2,650 from the victim's housemate, Ms Guan Li, 40.

Tanaka was given 14 months' jail in January 2016 for housebreaking and theft, while Foo was given probation in 2015.

Deputy Public Prosecutor Charleston Teo said Wong was with the two co-accused in an Internet gaming cafe at Geylang Road on March 31, 2015, when he suggested robbing prostitutes.

They found about 10 contact numbers of prostitutes from the Internet and started making phone calls.

Ms Xiao responded and at about 2am the next day, they arrived outside her house at Prome Road in Balestier. The men agreed that Wong would enter the house first, while Tanaka and Foo would hide behind a tree and rush in after Wong.

After Wong had entered Ms Xiao's home, she saw the other two men and immediately closed the door. Wong told her he needed to speak to his friends who were outside. He stepped out of her house and the trio came up with another plan which involved Foo entering the house first, followed by Wong and Tanaka.

Wong called the victim again and convinced her to provide her services by increasing the fee to $300.

DPP Teo said after the victim opened the door, Foo entered the house and prevented her from closing the door so that Wong and Tanaka could go in. Wong punched Ms Xiao in the face, and both he and Foo pushed her head several times.

They warned her that they were police officers, with Foo flashing his ITE identification card. Tanaka guarded the victim in the living room while Wong and Foo stole $300 and two mobile phones from her room.

Her housemate, Ms Guan, was in the toilet when she overheard the commotion. She left the house via the back door, and returned after the three men left. She found $2,650 worth of property missing from her room.

Wong was represented by lawyer Henry Lim who was assigned to the case under the Criminal Legal Aid Scheme. He could have been jailed for up to 14 years and given at least 12 strokes of the cane for robbery.

The maximum penalty for theft is seven years' jail and a fine.