COMMERCIAL premises have virtually no protection against a determined arsonist even if they are fitted with the most up-to-date fire precautions, a top British fire prevention expert said last night. Dr Gordon Cooke, fire safety engineering specialist at the United Kingdom's national Fire Research Station, said even furniture which met the top UK standards for fire resistance would not have lasted long against an arson attack. ''Furniture is supposed to be resistant against an accidental fire, for instance a lit cigarette or part of a burning newspaper. ''If several litres of fuel were spread over it, it would be bound to catch fire.'' Dr Cooke said a water sprinkler system could also be ineffective against an oil based fire. ''If you add water to a chip pan fire then you get a big explosion which scatters droplets of burning fat everywhere, a fireball. ''A water sprinkler could work though, if the liquid fuel were spread very thinly.'' But a construction industry expert said flammable materials used in the construction of bank interiors should be banned following yesterday's tragedy. The acrylic security screens used instead of glass in many of Hong Kong's banks give off toxic fumes when alight, according to Lam Chuk-kee. Mr Lam, whose company has fitted out shops, offices and helped in the interior design of banks for the past 10 years, claims many banks may only now change their security screens. ''Something in the bank gave off toxic fumes,'' he said. ''What is there inside the bank? There are no carpets, little furniture and everything is usually made out of marble. ''But tests on acrylic screens have shown they burn very easily and give off toxic gas.'' He said up to 80 per cent of banks in Hong Kong used acrylic screens rather than toughened glass. Acrylic was cheaper and easier to work with and fit. ''The fire spread so quickly. Something must have been fuelling it.'' Banks are classed as commercial buildings, the fire safety of which is governed primarily by the Buildings Ordinance and the Fire Service Ordinance. Fire safety must be taken into account in the construction plans for commercial buildings. Fire Services check that a new building complies with fire regulations - which vary from building to building - but take into account access and ventilation and provide for fire prevention equipment. All commercial buildings now require sprinkler systems, but those built before 1973 do not because they come under an earlier code of practice. Yesterday's tragedy happened in a 1964 building which had no sprinkler system. Deputy Chief Fire Officer Kwok Jing-keung, of the Fire Prevention Bureau, said he thought banks were generally safe. But he said: ''There is no legislation to empower the fire services to install sprinklers in old buildings. We would welcome such a power. ''However, it is difficult because some buildings may have structural difficulties.'' But he admitted that since a fire in the International Building in Central in 1992, more than 100 letters had been sent out to the owners of commercial buildings encouraging them to install sprinkler systems. ''The response was not satisfactory,'' he said. ''We only had a few people who responded.'' The Fire Department makes random checks of all banks to ensure owners comply with the requirement that fire prevention equipment is regularly and adequately maintained. All equipment, sprinkler systems if they are installed, fire alarms and extinguishers must be checked by registered contractors. Owners who do not conform or who are found to have blocked fire doors can be fined a maximum of $50,000 and jailed for a year. Dr Cooke said that if a bank had acrylic screens instead of glass ones, this could have contributed to a sustained fire. ''Glass is an inorganic substance. It is not affected by the fire until it reaches its melting point, when it simply cracks. ''An acrylic screen or any other hydrocarbon would help spread the flames. But the acrylic would have to be in very large quantities or the fire started very near it for it to have any lethal effect by itself. ''Most people in a room where a fire started would be dead by the time the acrylic started to have any effect.'' He said that most of the damage in a fire would be caused by the burning of the fuel itself, and the first thing it was in contact with, perhaps a carpet. The smoke could have been a lethal cocktail of gases. ''If polyurethane was involved, and it is used in the foam cushions of a lot of furniture, then hydrogen cyanide gas could have been given off. But this would only happen at high temperatures, around 800 degrees Centigrade.'' Any hydrocarbon fuel would have given off a mass of carbon monoxide, and this was the main threat to life, he said, but a number of other gases could contribute to it. ''Some of the gases would be irritants: by themselves they would be innocuous, but the effect would be to make people gag and choke. ''Their mucous membranes would swell up and they would find it very difficult to breath at all.''