Police said the methamphetamine had an estimated street value of up to A$42 million and added to the 14 tonnes of illicit substances seized in the past year.

A 29-year-old man has been charged with importing a commercial quantity of methamphetamine over the find, and two others - a 19-year-old man and a Chinese national aged 32 - charged with attempting to possess a commercial quantity of the drug. The maximum penalty for each offence is life imprisonment and an A$825,000 fine.

The arrests come after 558 kilograms of heroin and methamphetamine was smuggled into Port Botany in July. The discovery, not linked to the latest consignment, led to the arrest of seven people in Sydney, including four from Hong Kong.

An exchange of intelligence with their counterparts in Hong Kong helped Australian police make the HK$4 billion drug haul and arrest the four men - Lee Man, 42, Tang Hin-yiu, 61, Lam Chi-man, 29, and 34-year-old Lok Hung-kai.

Federal Police said the men, 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".

In August, 2010, New Zealand customs broke up a drug ring that smuggled up to NZ$17 million (HK$97 million) worth of pseudoephedrine, which arrived over 12 months at Auckland International Airport in machine parts imported from Hong Kong. Ephedrine or pseudoephedrine is a key component in the manufacture of methamphetamine.

However, local authorities have consistently denied that the raids and arrests are evidence that the city is becoming a drug smuggling hub.

Hong Kong's secretary for security, Lai Tung-kwok, said it was inevitable that some smugglers tried to use the city to traffic drugs but that the busts in July showed the strength of law enforcement here and the effectiveness of international co-operation.