POLICE were out in force in Wan Chai early today amid fears of a violent backlash to the gangland killing of triad leader Andely Chan Yiu-hing and his associate, Tse Chun-fung. Reinforcement officers were detailed to patrol the streets and bars of the busy nightlife area following the funerals yesterday of the two prominent Sun Yee On members. Intelligence gathered by the Organised Crime and Triad Bureau (OCTB) and Wan Chai detectives has led police to believe that rival groups are ready to muscle in on the activities of the Sun Yee On following Chan's murder. Both Chan, 32, and Tse, 29, were gunned down at 3.10 am on November 21, outside a Macau hotel in which they had been drinking. An associate, Ho Sun-wing, 26, was injured in the attack and is now in Hong Kong after being treated for his injuries under police guard. Investigators believe Chan was killed in retaliation for the murder in May last year of film producer Wong Long-wai, a 14K associate who had earlier slapped top singer Anita Mui at a bar for refusing to sing. Police believed gangs such as the Wo Hop To and the 14K were waiting for the funerals to take place before challenging the primacy in Wan Chai of the Sun Yee On. Officers say a power struggle has developed within the Sun Yee On for a successor to Chan, who was nicknamed the Tiger of Wan Chai. They believe the in-fighting has left them vulnerable to outside attacks - and also made them edgy. ''We suspect the Sun Yee On will be out breaking a few heads if they see any triads from other groups,'' said Superintendent Bob Youill of the OCTB yesterday. ''We will have officers on the street monitoring developments.'' Martin Samson, deputy district commander of Wan Chai police, confirmed that additional officers - both plain-clothes and uniformed - would be sent to patrol the streets and bars. He said there had been no indication of confrontation but added that his officers were prepared for the worst. Likely flashpoints in the event of violence were thought to be Lockhart Road, Percival Street, Canon Street, Jaffe Street and Tonnochy Road - all familiar territory to Chan, who began his triad life valet-parking the cars of restaurant customers for extortionate fees. Meanwhile, at least one officer investigating alleged extortion rackets run by Chan received a death threat before the murder, although it was unclear whether this was linked with the inquiry. About 25 members of the OCTB were at yesterday's funerals. Several mourners were lined up against a wall as they arrived and searched by the officers, who also checked them for tattoos, a common indication of triad membership. The numbers on their identity cards were recorded before they were allowed into the funeral parlour. After an angry exchange with mourners, police removed a wreath with words relating to the Wo On Lok triad. The Wo On Lok is a small force whose main interest involves public light buses in Kowloon. It is against Hong Kong laws to claim membership of a triad society. Wan Chai detectives were also present to identify any suspects still wanted over a plot hatched by Chan to extort protection money from restaurateurs in Causeway Bay's Times Square development and also for intelligence purposes.