NARCOTICS police say Hong Kong is facing an explosion in the use of the designer drug ice, which they predict will soon replace heroin as the territory's main drug. Seizures of the methylamphetamine drug have risen dramatically in the past five years. Arrests for possession and trafficking of ice have tripled in the past 12 months. The explosion is being fuelled by major production centres in China which feed off the abundance of the highly addictive drug's base component, the ephedra plant, which grows freely in southern provinces. Combined with the quick, cheap and relatively easy production process, that has led to a surge in the number of ice-making factories in Fujian, Xiamen and Guangdong. China is now the world's biggest producer of the drug. Detectives from the Narcotics Bureau say the number of people arrested for either trafficking or possession of the powerful stimulant has risen from just over 100 in 1995 to more than 300 so far this year. If current trends continue the figure is set to rise to more than 400 by the end of this year. The ephedra plant, which is processed to produce the stimulant ephedrine, is also used in traditional Chinese medicine remedies. Chief Inspector Bruce Hawkins of the Narcotics Bureau said: 'There is no doubt that globally the demand for ice and other amphetamine-type drugs have burgeoned dramatically and Hong Kong is part of that. 'It may seem difficult to imagine anything taking over from heroin as the main drug of abuse here but ice has the potential. It is easier and cheaper to make and, gram for gram, it gives addicts better value for money.' In the past three years, upwards of 200 kilograms of ice have been seized, compared with 18 kg in 1992 and 1.8 kg in 1993.