TAXI and minibus commuters face higher fares if the Government decides to phase out diesel light vehicles, a joint committee formed by operators warned yesterday. Taxi and minibus associations have united to urge the Government to drop a plan which would force light duty vehicles to use unleaded petrol within five years after 1996. Legislators were told last week that the plan was being studied as an attempt to reduce emissions of pollutants in diesel fumes. A spokesman for the operators, Ng Kwok-hung, said fares could double if the drivers had to switch to petrol. 'Petrol is more expensive, while diesel vehicles consume less fuel for the same distance and are easier to maintain,' said Mr Ng. 'We would loose our competitiveness, even if the government let us increase the fares to whatever we wanted. I don't think we could survive.' He said the most effective way to reduce emissions from diesel engines while maintaining their viability was to install turbines and filters. It was unfair to ban light diesel vehicles while heavy ones such as trucks and buses would not be affected, Mr Ng said. He asked the Government not to ignore their views as the Environmental Protection Department had refused their requests to discuss the issue since December. But Assistant Secretary for Planning, Environment and Lands Laurie Lo Chi-hong said the branch was still studying the proposal and was not ready for public consultation. He said it 'was premature' and he hoped they would be able to discuss it within 'one or two months'. But he stressed that using petrol engines was an effective way of improving air quality because commercial diesel vehicles released a large amount of pollutants daily. He said it was impossible to force heavy vehicles to use petrol because there were no heavy duty petrol-powered vehicles on the market.