In the first shipment, crystal meth was stored inside three transformers - large devices designed to transfer electricity. The seizure led officers to a Sheung Shui warehouse on March 24 where another 253 kilograms of the drug ice was found.

A total of 700kg was seized, amounting to the biggest ice seizure in Hong Kong's history. Customs officers have now launched a manhunt for the drug syndicate's mastermind.

The first shipment was found on March 18, customs' airport drug investigation team head Lee Man-lok said.

Officers were initially suspicious as Mexico rarely exports industrial machinery. Further, not only did the sender dispatch the goods under his own name and commission a mainland company to transport the goods but it was also his first shipment to Hong Kong - a modus operandi similar to previous drug trafficking cases.

Since X-ray images of the transformers looked suspicious, officers disassembled them to find what they seemed to be motor oil inside. Subsequent drug tests identified meth in the liquid. Indeed, the three transformers contained some 447kg of the drug.

The 44-year-old owner of a transport company - which was set to collect the transformers at the airport - was subsequently arrested.

He had been commissioned by a mainland logistics company to transport the transformers to a Fan Ling warehouse for temporary storage.

"It is believed someone was using the logistics company to remotely conduct drug trafficking," Lee said, adding mainland authorities were contacted afterward to launch a joint operation.

Six days after the initial drug find, officers raided a Sheung Shui warehouse where they discovered 10 cylindrical shock absorbers - devices used to dampen shock impulses - containing the drugs.

A 43-year-old man in charge of the warehouse was arrested. Both suspects have since been released on bail.

"They entrusted a local logistics company to store them and would arrange to transfer the goods later during the whole process, the traffickers did not need to show up," Lee said.