The pesticide is sold in 48 countries all of which classify it as non-toxic or low-toxic, but Hong Kong offers no distinction: all pesticides are seen as toxic under the Pesticides Ordinance and as such are subject to controls.

'We were told [by the Agriculture and Fisheries Department] we had to state on our labels that the product was toxic even though it's not,' Mr Thoni said. 'We haggled for 21/2 years just over labelling.' This delay cost BioCycle millions of dollars, he said.

Eventually, the department exempted the company from having to label its pesticide as 'toxic' and 'poisonous', but still the label must carry strong warnings that there is no specific antidote for consumption of the product, to keep it away from children and not to spray it near food - all of which, Mr Thoni says, are unnecessary.

He said the warning also gave the wrong message to potential buyers.

The law also required BioCycle's Kowloon Bay manufacturing plant to provide protective overalls, boots, gloves and glasses to workers, even though the chemical they handled - a water-based synthetic pyrethrum called permethrine - was harmless.

By contrast, it took BioCycle 30 minutes to get an exemption from toxic chemical laws when it set up in Singapore.

Mr Thoni said department officers had privately acknowledged there was a problem with the legislation, but they were hamstrung by the law.

But a senior departmental officer, Fong Chun-wah, said the laws worked well and were in line with United Nations Food and Agriculture Organisation guidelines.

'If a product is considered to be very low-toxic this can be reflected on the label if the company provides data to justify its claims,' he said.

'We will not compromise our safety standards, and the labelling requirements are intended to help the user.' The Pesticide Ordinance was last reviewed in 1991.