The substance was used as a herbal medicine and has stimulant-like effects. When abused, the substance may cause nausea, constipation, increased urination, loss of appetite, seizures, hallucinations and withdrawal symptoms.

Customs officers inspected an air transshipment consignment, declared as Mitragyna speciosa, from Indonesia to the US via Hong Kong last Thursday.

Green powder was found in 124 carton boxes, tested to contain 2.5 tonnes of mitragynine.

Mitragynine, a major compound available in a plant known as Mitragyna speciosa, also known as kratom, was listed in the first schedule to the Dangerous Drugs Ordinance on August 13 this year.

Customs reminded that importation of dangerous drugs requires an import license and import certificate issued by the Department of Health.

A valid export authorization or diversion certificate from the exporting country will also be required.

Transshipment of dangerous drugs also requires a removal license issued by the Department of Health.

Trafficking in a dangerous drug is a serious offense that is liable to a fine of HK$5 million and life imprisonment.