Customs officers are seeking new legal provisions to make it easier for them to prosecute drivers who use illegal fuel. Under a clause to be put before the next legislative session, drivers will be liable to prosecution if they are found using diesel with a sulphur content more than 0.05 per cent by weight - the maximum legal limit. Taxi drivers, who normally operate on shifts, were worried a driver might be wrongly prosecuted for illegal fuel bought by colleagues, but the Government said receipts and timing would be checked to prevent this. Illicit oil smuggled from the mainland and sold cheaply in Hong Kong generally has a sulphur content of more than 0.05 per cent. In the first six months of this year, Customs arrested 71 people for using illicit fuel after checking 1,547 vehicles and 123 boats.