THE surgeon who carried out Hongkong's first heart transplant has severed his official link with the University of Hongkong, raising fears of a lack of cardiac surgeons in the public sector. The move by Professor Mok Che-keung, who has been dividing his time between his public and private practices for two years, will concentrate more on his private business. But the heart surgeon will keep his office at Grantham Hospital - Hongkong's major heart centre in the public sector - where he is an honorary consultant. Last week Professor Mok insisted he would still ''render my service free to the university'', although his contract ended last month. He said he was willing to take part in future transplant operations. Professor Mok claimed he would not spend all his time serving private patients, and that since he was not running a private clinic but handling referrals from private doctors, he would be more ''readily available'' when his service was required in the public sector. But the chairman of the Hongkong Public Doctors' Association, Dr Chan Chi-kuen, said he was alarmed at the lack of cardiac surgeons in Hongkong, and the fact that the public had to rely on the expertise of ''one or two persons''. The Hospital Authority does not keep figures for cardiac surgeons, but not more than 10 are estimated to be serving in the public sector. ''The Government has a responsibility [in training]. There should be long-term planning. We should not wait until somebody has gone before we realise there is a shortage,'' he said. It was unhealthy when ''our public service depends on the goodwill of Professor Mok'', he said. Dr Chan said the long waiting time was a concern, and he warned that some patients could die before receiving necessary surgery. ''We have a long waiting time for cardiac surgery. I have come across some who could not wait that long,'' he said. Dr Chan criticised the slow development of cardiac surgery in Hongkong. ''In the past decade, not many surgeons have been trained. We should definitely train more in future,'' he said. Professor Mok said patients could wait up to 12 months for non-emergency cardiac surgery, but he attributed this more to a lack of support staff - such as intensive care and operating theatre nurses - than surgeons. Professor Mok said he held frequent discussions with the Hospital Authority to address these issues, but had yet to receive a reply to his proposals. Professor John Wong, head of the Department of Surgery at the University of Hongkong, agreed there was no point producing more cardiac surgeons if ''these other problems cannot be addressed''. He said the university had tried to hold on to experienced doctors by offering them special contracts, such as the one given to Professor Mok enabling him to work privately. Such privileges are believed to have caused anxiety among some university staff who, unlike Professor Mok, usually have to forward to the university what they have earned in the private sector. Professor Mok, in a bid to end what others believe to be the ''best of both worlds'', decided not to draw a salary from the university. He is now its honorary professor. But Dr Chan said doctors had always doubted whether the scheme of part-time employment would work. There was a potential conflict of interest with part-time professors and those who occupied an honorary position in hospitals, he said. ''When a public and a private patient both need to be seen and at the same time, who will he see first?'' he said.