Several suspected ringleaders of the smuggling operation were arrested in the September 19 raid, including a Hong Kong man identified as Chan Wong-sun.

Police said the group was planning to sell the ketamine for an estimated 120 million yuan in Guangdong, netting a 40 million yuan profit.

Mr Liu said the ketamine was made in India and shipped to Yantai via Singapore and the South Korean city of Pusan. It was then to be sent overland to Guangdong.

Guangdong police received information in July that Chan, Canadian nationals Kung Ka Sam and Xiang Bao, and a Guangdong man, Yang Weiyuan , were planning to smuggle a large quantity of the drug from India to the mainland.

Mr Liu said the group allegedly prepared two containers in Mumbai for the smuggling operation and was planning to send one without the drug on a trial run.

But typhoon damage to a shipping warehouse in Mumbai delayed the departure of the test shipment and the traffickers were forced to send the ketamine consignment ahead of schedule.

Officers in charge of the sting operation suspected the smugglers would make two shipments and asked Pusan police to take no action when the ketamine arrived in the South Korean city in case the route for the second shipment was changed.

Both shipments arrived in Yantai by September 10 and officers swooped on the smugglers as they prepared to send the haul to Guangdong.

Mr Liu said Hong Kong police supported the crackdown.

'The suspects are mainly based in Hong Kong and the funds for the operation were also in Hong Kong,' he said.

Mr Liu added that the main suspects confessed the shipments were part of a bigger plan to open up a new drug smuggling channel from Yantai.

'The drug dealers felt that strict monitoring along Guangdong's coastal areas had increased the cost and difficulty of smuggling so they shifted their attention to ports in northern areas,' he said.

Mainland police have alerted Interpol to be on the lookout for Kung, the only one of the four main suspects not in custody. Mr Liu said the specific circumstances of an alleged crime would determine whether Chan would be tried on the mainland.

However when asked about the bust yesterday, Hong Kong police said that they had no details of an arrest of a man from the city on the mainland.

'Based on the information we have so far, none of the arrested people is a Hong Kong resident. But we will keep an eye on this,' a Hong Kong police spokesman said.

Beijing will host a China-Asean drugs summit next week to discuss ways to counter trafficking. The meeting is expected to yield a joint declaration on drug prevention and crackdowns.

Additional reporting by Kristine Kwok