Female celebrities photographed taking part in sex acts with Edison Chen Koon-hei could be called by the defence to give evidence in the trial of the computer technician charged with circulating the images. Defence barrister Kelvin Lai confirmed that an application had been made to Kowloon City Court on Wednesday to call four female witnesses in defence of Sze Ho-chun. Mr Lai declined to reveal the identities of the witnesses but said the four would be capable of providing 'relevant and material evidence'. The photographs that led to Sze being charged were published on the internet and then in Hong Kong's Chinese-language press early last year. They included some of the biggest names in local show business. Those purported to be involved in sex acts with the actor-singer include Gillian Chung Yan-tung of pop duo Twins, actress Cecilia Cheung Pak-chi, former actress Bobo Chan Man-woon, model and actress Rachel Ngan Wing-sze and Vincy Yeung Wing-ching, niece of entertainment tycoon Albert Yeung Sau-shing. All have been rumoured to have been romantically linked to Chen apart from Yeung, who has admitted having a relationship with the star. Mr Lai will submit his reasons for calling the women before Chief Magistrate Tong Man on March 9. Mr Lai said the magistrate would make a decision after hearing submissions from both parties, including prosecutor Hayson Tse Ka-shu. Sze's trial is set for 10 days from April 6 at Kowloon City Court. Sze has denied three counts of aiding the distribution on the internet of photographs of Chen performing sex acts with the actresses and singers. The prosecution, defence lawyers and the chief magistrate will attend the Supreme Court of British Columbia in Canada next week for a hearing to collect evidence from Chen, who has refused to return to Hong Kong. Solicitor Stephen Hung Wan-shun, a council member of the Law Society, said witnesses might not be called to give evidence at the trial even if summonses had been issued. Judges had the power to require an explanation from the defence lawyer who applied for summonses to be issued to witnesses, and they could decline the application.