An exchange of intelligence with their counterparts in Hong Kong helped Australian police land a HK$4 billion drug haul and arrest four Hong Kong men suspected of being part of a smuggling gang, it was revealed yesterday. The raid is the latest in a series of large drug hauls linked to Hong Kong. The city's security chief said it was inevitable that some smugglers tried to use the city to traffic drugs but that the busts showed the strength of law enforcement here and the effectiveness of international co-operation. Australian police and customs seized a record 306kg of Ice and 252kg of heroin in Sydney on Monday, arresting seven people. Four of them were Hong Kong men: Lee Man, 42, Tang Hin-yiu, 61, Lam Chi-man, 29 and Lok Hung-kai, 34. Secretary for Security Lai Tung-kwok said the case sent a strong message to potential drug smugglers. 'Co-operation in tackling international drug trafficking is an ongoing aim of all the law enforcement agencies ... This substantial [seizure] is one of the results,' he said. Hong Kong police are refusing to comment on the case. But it is understood that the force exchanged intelligence with the Australian police. The Australian Federal Police said the Hongkongers, who lived in a flat in Sussex Street in Sydney's central business district, played multiple roles, from facilitating the import of the drugs to unpacking and handing narcotics over to 'runners'. The four were charged with conspiracy to import Ice and heroin. Lam and Lok were also charged with attempting to possess a commercial quantity of Ice and heroin. None applied for bail in court on Tuesday. The case was adjourned until October 17. Australian police refused to comment further, saying that investigations in Hong Kong were ongoing and further arrests could be made. The latest figures from the government's Fight Crime Committee show that police and customs seized 121kg of cannabis in the first half of the year, up from 8kg in the same period last year. Some 559kg of ketamine was seized in the first half, up from 157kg last year. Lai said the increased seizures were down to two individual drug busts by customs at borders and cargo terminals. He said 70 per cent of drugs were seized at such points. Customs announced last month a record 649kg of cocaine had been seized in a shipping container from Ecuador, while a record haul of ketamine was seized in June. Local authorities have consistently denied that the raids are evidence that the city is becoming a drug smuggling hub.