Legislation in Hong Kong criminalises "insults to the national anthem of China" and was implemented in June 2020.

The song Glory to Hong Kong was written in 2019, was played widely during the pro-democracy protests and was considered by many demonstrators to be their national anthem.

It was then banned in 2020 after China imposed national security laws in Hong Kong that punished what the country's Government defined as secession, subversion, terrorism and collusion with foreign forces.

Sentences as extreme as life in prison can be handed out.

Police in Hong Kong said China's national anthem should have been played at the final between Hong Kong and South Korea in Incheon.

"Police will take follow-up actions seriously in accordance with the law on whether the incident has breached the National Anthem Ordinance or any other legislation, including the Hong Kong National Security Law," a police statement said, as reported by Reuters.

Asia Rugby said it deeply regretted the incident which was caused by a "simple human error from a junior member of the local Organising Committee playing a song downloaded from the internet instead of the correct anthem".

After the match, which Hong Kong won 19-12, a public apology was announced in the stadium and the correct anthem was played.

Given the incident took place in South Korea, it is unclear what action authorities in Hong Kong could take. 

The incident comes days after Hong Kong journalist Paula Leung was jailed for breaking the law after waving a British colonial-era flag to celebrate Cheung Ka Long's fencing gold medal at the Tokyo 2020 Olympic Games.

She was imprisoned for three months after pleading guilty to the charge of breaking the anthem ordinance law.

The 42-year-old online news reporter was spotted waving the British Hong Kong flag at a shopping mall during a screening of the Tokyo 2020 awards ceremony when Cheung collected his gold medal.