COMPANIES which supply medical gas to hospitals could require two licences in future - one from the Fire Services Department and another from the Department of Health. Director of Health Dr Margaret Chan Fung Fu-chan said last night that two pharmacists had returned from Britain, after training in the technical inspection of medical gas producers. 'As far as we're concerned, we're ready. We need to tidy up that piece of law,' Dr Chan said. The announcement came as Hong Kong Oxygen blamed 'human error' for a mix-up in which bottles of carbon dioxide were given 'medical air' labels and delivered to the United Christian and St Teresa's hospitals on Friday. 'This incident of wrong labelling appears to be a result of human error,' said deputy managing director Mike Huggon. 'Until we have identified the probable cause of the incident, we are doing additional checks on medical gas cylinders before they are released for delivery to our customers.' The incident has resurrected fears raised in 1989, when restaurant critic Shirley Boyde, 55, died after receiving nitrogen from a Hong Kong Oxygen bottle marked 'oxygen' at the Canossa Hospital, and three pregnant women received carbon dioxide from a bottle marked 'nitrous oxide' at the Caritas Medical Centre. Dr Chan said controls could be tightened by allowing the Health Department to set up its own inspections and requirements, parallel to Fire Services checks. 'At the moment, the Fire Services Department is the licensing authority. But we are in the process of amending the Pharmacy and Poisons Ordinance - we would like to license medical gases as pharmaceutical products,' Dr Chan said. Since the 1989 incidents, experts from the British-based Medical Control Agency had accompanied Fire Services and Health officers on inspections of the Hong Kong Oxygen Company every 18 months. The last inspection was in January 1995. Medical legislator Dr Leong Che-hung yesterday led a push for medical gas to be regulated by Pharmacy and Poisons inspectors as soon as possible. 'Medical gas is just like a drug - if you make a mistake, you're going to kill people,' he said. Dr Leong criticised Hong Kong Oxygen for failing to alert all hospitals until Sunday, although clients which received bottles from the suspect batch were told on Friday. 'It is extremely irresponsible. How could they guarantee that these bottles couldn't have got into another hospital,' he asked. Similar mistakes made in any of the thousands of gas bottles sold for industrial use could be equally dangerous, Dr Leong said.