S Korea warns citizens against smoking pot in Canada

South Korea has warned its citizens against smoking marijuana in Canada, telling them that even though the country legalised weed last week, using it there was still an offence under Seoul's own laws.

Consumption, possession or sale of illegal substances are criminal offences under South Korea's tough drugs legislation.

Last Wednesday, Canada became the world's first major economy to fully legalise cannabis, including for recreational use, sparking celebrations as the nation embarked on the controversial policy experiment.

But South Korea's criminal laws apply both territorially and personally, officials said, meaning that its citizens would still face punishment for smoking weed even if they did so in Canada.

"South Korean individuals who use marijuana (including purchase, possession and transport) -- even in regions where such acts are legal -- are violating the law and will be punished accordingly," the South Korean embassy in Canada tweeted last week.

"So please beware," it said.

In South Korea, prominent figures or celebrities have often made headlines for smoking marijuana at home or abroad, with offences in foreign countries revealed by tip-offs to police.

Some spent years in jail during the 1970s or 80s when the country was under military rule, but in recent years many were merely fined or given suspended terms.

South Korea is not the only country that punishes people for foreign narcotics use.

In Singapore, which has some of the toughest drugs laws in the world, citizens and permanent residents face up to 10 years in prison if found to have consumed illegal substances outside the city-state.

Random urine checks are carried out at Changi Airport and other entry points.