A man and his two alleged accomplices duped a sex worker into thinking they were policemen conducting a raid before taking her money and mobile phone.

Liu Aik Kang, 25, who is jobless, pleaded guilty yesterday to one count each of theft and cheating by personation.

The court heard the two other men are Tan Shi Feng, 29, who was a navy regular when he allegedly committed the offence, and Liu's cousin Hu Zhihao, 26.

Deputy Public Prosecutor Foo Shi Hao said Hu is a former navy regular who introduced Tan to Liu.

On May 16, Liu entered an apartment in Jalan Sultan and stole about $8,000 worth of valuables, including a laptop computer and a camera. Closed-circuit television footage showed the Singaporean entering the unit. Liu surrendered to the police eight days later.

While out on bail in early June, Liu came up with the plan with Tan and Hu to cheat a sex worker. On June 23, Tan went online and came across the sex worker's advertisement.

The three men later went to a Balestier Road condominium unit where the 31-year-old woman worked.

Tan went into the apartment while the other two waited outside. After making sure the coast was clear, he let Liu and Hu in.

On entering the apartment, Liu identified the three of them as police officers. Hu had a video camera to record the "raid".

Led into believing the trio were law enforcers, the woman allowed them to search the flat.

DPP Foo said the trio took $15,000 and a mobile phone worth about $600. They were arrested the following day.

Liu is expected to be sentenced on Nov 29, while the other two men will be dealt with separately. Court documents did not say if action was taken against the sex worker.