A man posing as a police officer raped and then robbed a woman working illegally as a prostitute, a court heard yesterday. Wong Ka-wai has pleaded not guilty in the District Court to charges of rape and robbery stemming from a report made to police on May 26. It is alleged that at about 12.15pm on that day, 29-year-old Wong, posing as a police officer, knocked on the door of a fifth-floor flat at Lai Kei Mansion on Nathan Road in Yau Ma Tei. Prosecutor Jimmy Kwong said Wong told the woman who answered the door that he was a police officer and demanded to check her identity card. Upon seeing a substantial amount of money in the woman's wallet, Wong then pretended to talk into an earpiece and gave the impression that he was part of a larger team of police raiding the premises in search of prostitutes, the court heard. The woman testified yesterday that she was scared that Wong, whom she singled out in court as her attacker, would reveal she had been working as a prostitute and arrest her. She was in possession of a seven-day tourist visa and was not allowed to work in Hong Kong. She has been granted immunity from prosecution so she can testify. 'I told him that I did not work here and that I would leave today - please let me go,' she said. 'Then he asked me, 'What advantages will you give me?' Then he pushed me down and made me do those things with him,' she said. 'He said, 'You do this with me ... I will tell them not to arrest you and let you go'.' The woman testified that Wong forced her to crouch on the bed while he sexually assaulted her. She did not believe that a condom was used during the rape. Wong then allegedly stole her wallet, which contained $3,800 and US$700, and her mobile phone and fled the scene. Mr Kwong said the woman found the building's caretaker who reported the matter to police. The woman originally reported only the robbery, but revealed the rape after asking attending police officers for a medical examination because she was afraid of contracting HIV. The trial continues before Mr Justice Derek Pang Wai-cheong on Monday.