Minibus operators' protests against LPG are 'premature', environmental protection head Rob Law said yesterday. He said the Government would not force operators to make a switch to liquefied petroleum gas until satisfactory trials were conducted. The Environmental Protection Department director was responding to a campaign of opposition launched by operators of the 4,350 minibuses on Tuesday. 'At the moment, their reaction has been a little bit premature. Perhaps they are getting off their shot in the negotiations,' Mr Law said. He said the department had no intention of pushing ahead with the scheme until the infrastructure was in place. 'After the trial, the minibus drivers will be able to see how the vehicle works and how it performs economically,' Mr Law said. The department will consult operators next week. Mr Law said LPG vehicles were a proven new technology that could be used to combat air pollution. The department would not object to alternatives such as electricity being used in trials, but he said: 'In the case of electric vehicles, they are extremely heavy and very expensive. Obviously, these are problems the minibus operators have to consider if they participate in the trial.' The Secretary for Planning, Environment and Lands, Gordon Siu Kwing-chue, said he would not rule out testing electric vehicles. Operators have expressed concern that they cannot afford the switch to LPG.