Metro family scion Ong Jenn had enough cannabis at home to last him between one and seven months, yet he ordered more drugs from his supplier, enough to feed his habit for up to another 10 months.

A prosecutor highlighted this to the High Court yesterday, arguing that it was absurd for Ong to be "stockpiling" so much drugs - enough for 17 months - purely for his own consumption.

Ong, 43, originally faced two charges of abetment to traffic in controlled drugs, namely 92.68g of cannabis and 385.1g of cannabis mixture.

His supplier, Mohamad Ismail Abdul Majid, had called him in October 2014, asking if he wanted to buy cannabis. Ong agreed to buy 500g for $5,000. Ismail was arrested before the drugs were delivered.

After a six-day trial, a district judge accepted Ong's explanation that the drugs were solely for his own consumption and reduced the charges to that of attempted possession in May last year.

Ong is currently serving a two-year jail term after pleading guilty to the reduced charges.

The prosecution has appealed, arguing that Ong should be convicted of the original charges of abetment of trafficking, which carries a mandatory minimum sentence of five years' jail and five strokes of the cane on each count.

Yesterday, Deputy Public Prosecutor Kow Keng Siong argued that text messages between Ong and two female friends show that he agreed to sell or share the cannabis with them.

The DPP said the sheer quantity of the drugs gives rise to the inference that Ong had ordered the drugs from Mohamad Ismail for the purpose of trafficking.

He said Ong had given conflicting accounts of his consumption rate, but the trial judge "unquestioningly accepted" his unsubstantiated claim during cross-examination that he used 140g every two weeks.

The DPP argued that the judge was wrong in concluding that Ong was a "man of means" who was not particular about spending $5,000 on drugs. Ong, a business development manager with Metro Holdings, earned $7,000 a month.

Even if Ong was a "man of means", there is no reason why people from well-to-do families cannot traffic in drugs, said the DPP.

Ong's lawyer, Senior Counsel Tan Chee Meng, argued that his client was a "heavy user" - having formed a cannabis habit when he was studying in the United States - but not a trafficker.

Mr Tan said Mohamad Ismail had repeatedly called Ong to buy the drugs; despite having enough at home, Ong reluctantly agreed to buy more drugs because of the pestering.

The defence also submitted dividend vouchers to show that Ong had income apart from his salary. Details were not revealed in open court.

Ong, with his head shaved and looking visibly thinner, appeared relaxed during the appeal. He will be tried later this year on another set of drug charges.

Justice Hoo Sheau Peng will make a decision on the appeal at a later date.