A man in Singapore who attempted to frame his estranged wife by planting cannabis in her car has been sentenced to almost four years in jail.

Tan Xianglong, 37, planted what he thought was more than half a kilo of cannabis between the rear passenger seats of his wife's car, assuming it was enough to warrant the death penalty for drug trafficking.

Singapore has some of the world's toughest anti-drug laws, which the government says are necessary to deter drug-related crimes.

Less than half of the substance Tan planted turned out to be cannabis, though. The rest was filler.

Tan "intended to scare the involved party and to also get her in trouble with the law," according to court documents.

"He understood that the involved party would be wrongly arrested and charged with a serious crime if his plan succeeded."

He was sentenced on Thursday to three years and 10 months in prison for cannabis possession. The court also considered a second charge of illegal planting of evidence.

Tan and his wife married in 2021 and separated a year later. They could not file for divorce because Singapore allows it only for couples who have been married for at least three years.

Tan believed he might be granted to exception to that rule if his wife had a criminal record.

In Telegram chats with his girlfriend last year, he said he had hatched the "perfect crime" to frame his wife.

On 16 October, he bought a brick of cannabis from a Telegram chat group, weighing it to make sure it exceeded 500g (1.1lbs), and placed it in her car the next day.

What Tan seemingly didn't account for was the fact that his wife's car was equipped with a camera, which sent her a phone notification alerting her to a "parking impact".

When she checked the live footage, she saw her estranged husband walking around her vehicle and reported him to the police for harassment.

In the course of their investigation, police searched the car, found the drugs and arrested Tan's wife.

But after finding no incriminating evidence against her, they then turned their investigation towards Tan himself, and arrested him.

Tan's lawyer tried to argue that he was suffering from depression when he committed the crime, but the court rejected this, citing doctors' findings that he was not suffering from any mental disorder.

Depending on the substance and the amount seized, drug possession in Singapore is punishable by imprisonment while drug trafficking can be punishable by death.

Although Tan was liable to be sentenced to five years in prison, he got a lower term because he co-operated in the proceedings and pleaded guilty early in the trial, according to court documents.

Last year, Singapore executed two convicted drug traffickers over a five-month period, defying opposition from international human rights groups.