Cooperation key: Narcotics Bureau Chief Superintendent Peter George Else says the bureau could not have succeeded without help from its foreign counterparts, and that this seizure has hit the syndicate responsible very hard indeed.

Police believe they have hit a drugs syndicate hard after arresting two men and seizing a record 550 kilograms of the party drug ketamine - worth about $85 million at street level.

The two men, both aged 53, were each charged with two counts of trafficking in dangerous drugs and will appear in Tsuen Wan Magistrates' Court tomorrow morning.

The two were arrested as they left on a factory unit on Wang Lung Street in Tsuen Wan on Tuesday morning. Police found about 50kg of ketamine in the two suitcases they were carrying. A search of the unit they had left yielded another 500kg of the drug.

"This is very significant, 550kg is half a tonne - a very, very significant seizure, not just locally but by international standards," Narcotics Bureau Chief Superintendent Peter George Else told reporters at a press briefing this morning.

"It has hit its syndicate very hard, very hard indeed. It's worth $85 million at street level, so it's had a very significant impact not only on the syndicate that was responsible for bringing this in, but it also would have had a significant impact on ketamine suppliers in Hong Kong and within South China."

The Narcotics Bureau had been investigating for about six months, and liaising with overseas law-enforcement agencies, before officers swooped down on the industrial building.

"We don't know the exact source of the drugs, but it's highly likely they came in a container given the volumes," Mr Else said.

"Obviously, if this was a bulk storage location, there may have been earlier withdrawals, and if it was a sizeable consignment of that nature, it would normally come in by container."

This was the third in a series of raids the bureau has carried out this year. In January, it seized 151kg of ketamine in Sai Kung, and a month later, it seized 200kg of the drug in Cheung Sha Wan.

Mr Else added the bureau could not have succeeded without help from its foreign counterparts.

"The key to stopping the drugs trade is international cooperation, and it's an area where police forces have long been cooperating across even political differences. There has always been very significant cooperation in place against drugs and we have excellent cooperation with overseas agencies. I believe we offer them excellent liaison when they come to us for assistance, but that's really the solution to the fight against drugs."