Sydney man Peter Gardner has begged a Chinese court for mercy, claiming he believed he was trafficking steroids when around 30kg of ice was found in his luggage bound for Australia.

The 25-year-old appeared in court yesterday for his one-day trial and will soon learn whether he will face the death penalty.

Gardner claimed he was duped into carrying the drugs – which had an Australian street value of $18m - by a complex crime syndicate with connections to baggage handlers in Sydney.

His lawyer said Gardner’s attitude in helping police identifying drug kingpins should grant him leniency in the case.

Police presence outside court in Guangzhou. (Supplied)

The dual Australian and New Zealand citizen has been in custody since November, when Chinese authorities intercepted his suitcases in Guangzhou.

Customs officials were forced to cut open his luggage as the zips had been superglued shut.

Chinese law states anyone caught with more than 50 grams of methamphetamines or heroin is liable to face capital punishment.

Gardner has claimed he thought he was carrying steroids in his luggage. (Supplied)

Local media has described it as the single largest ice haul in the country’s law enforcement history.

Gardner’s girlfriend, Kalynda Davis, was detained for several weeks before being released and allowed to return home to Sydney.

Gardner's partner Kalyna Davis was released after being arrested over the smuggling plot. (Supplied) (Supplied)

There is no indication she was involved in the operation.