Operators say passenger charges will increase if they are forced to use the more expensive ultra-low sulfur diesel The city's two major ferry operators warn passenger fares may increase if the government requires them to use low-sulfur fuel. The warning, by Star Ferry and New World First Ferry, comes as the Marine Department says that 900 locally licensed diesel vessels will have to cut emissions once a proposed anti-pollution law comes into effect. It will bring vessels' emission standards into line with those for land vehicles. The department is also studying the feasibility of making passenger ferries use ultra-low sulfur diesel (ULSD) as part of measures aimed at slashing the emissions of sulfur and nitrogen oxide by sea and ocean-going vessels. The more expensive ULSD has been used by city diesel-powered road vehicles since 2000. However, only 160 government launches operated by various departments have used this fuel at sea. Both ferry companies have resisted the proposed switch to the more expensive fuel, saying the extra financial burden will mean higher fares for passengers. Both companies said their ships already used light diesel that contained only 0.3 per cent sulfur, but was $1.80 per litre cheaper than ULSD. Unlike road vehicles, ferry emissions have not been regulated by the environment department. Instead, vague rules in the shipping law - which make it an offence for ships to emit enough smoke to create a nuisance - have been enforced by the Marine Department. Under this law, the department has received 51 complaints and issued 18 warnings from 2002 to 2004, only one of which resulted in prosecution. The Marine Department's pending laws are in line with regulations adopted by the International Maritime Organisation, a United Nations agency, in May. These capped the sulfur content of sea and ocean-going vessels' fuel and cut their allowable emissions of nitrogen oxides. 'We are now incorporating these requirements into the law,' a spokesman for the Marine Department said. 'We believe most locally licensed ships have reached the required standard, as fuel oil currently supplied in the city contains less than 0.5 per cent sulfur.' A timetable for legislation and implementation has yet to be decided, the spokesman said. A spokeswoman for New World First Ferry, which last week won approval to increase fares by 6.5 per cent across the board, warned that it would be difficult for the company to convert its ships to ULSD, as the company was already running at a loss. 'The price of oil has already doubled over the past year, and it will become an even bigger burden if we switch to ULSD,' she said. A spokesman for Star Ferry said that the company used around 2.5 million litres of light diesel a year. Converting to ULSD could add $5 million to its fuel bill, which might increase pressure for a fare rise, the spokesman added.