An elevenfold surge in seizures of illegal drugs at land borders has prompted customs officers to step up intelligence exchanges and co-operation with mainland authorities.
Customs officers will also use more sniffer dogs and undercover agents to catch traffickers taking advantage of the busy flow across the border, especially over Christmas.
Officers are disguising themselves as travellers and mingling with visitors to carry out surveillance and identify suspicious travellers, a senior customs official says.
In the first 11 months of the year, customs officers seized 185.3kg of illegal drugs - comprising 152.8kg of ketamine, 19.7kg of cannabis, 11.4kg of Ice and 1.3kg of heroin - at land border checkpoints.
They detected 221 drug-trafficking cases and made 206 arrests. The biggest seizure was at the Man Kam To checkpoint in September - 140kg of ketamine.
In the same period last year they seized 16.7kg of drugs and arrested 207 people caught in 239 cases.
Among those arrested this year, 33 were under 21, with the youngest just 16. There were 42 young offenders in the same period last year.
Senior Superintendent John Lee Cheung-wing, head of customs' drug investigation bureau, said the increase in seizures was the result of stronger enforcement at land control points this year.
He said traffickers used different methods to conceal drugs and smuggle them into the city from the mainland.
Some tied packages around their bodies, some concealed the drugs in secret compartments of luggage and cross-border vehicles, while others swallowed packets of drugs.
He described a common tactic to smuggle ketamine as 'ants moving home'.
'Traffickers carry small amounts of ketamine and some try to smuggle as little as a dozen grams of the drug into Hong Kong.'
He believed this tactic was used to reduce losses in the event of detection by law enforcers.
'Our ... capability at border checkpoints will be further strengthened through enhancement of drug detector dog services and plain-clothes operations.'
Apart from at land border crossings, customs officers seized 479kg of illegal drugs, mostly at the airport, and arrested 254 people this year.
Lee said more than 10 airmail parcels, each containing about 1kg of cocaine, were discovered.
'The parcels were declared to contain books or metal parts, but cocaine was found hidden in hollowed-out books and metal parts,' the superintendent said.
'The investigation showed that the drug was smuggled from South America via Germany, France or the United States.'
Although investigations showed that most of the 664kg of drugs seized were not for local consumption, Lee said there was no evidence to suggest that Hong Kong was a drug transit hub.
He said customs would continue to co-operate with police in Hong Kong and on the mainland and overseas law-enforcement agencies to fight the drug trade.
Customs seized 664kg of drugs and arrested 460 people in the first 11 months of the year
In the same period last year they seized 596kg of drugs, and the number of people arrested was: 607