Hong Kong has its own national football team, but not its own anthem - so the Chinese one is played before games.

In recent years, the anthem has been booed more frequently before matches.

In 2017, China's parliament, the National People's Congress, extended a law on disrespecting the anthem to Hong Kong - but it has not yet been adopted there.

China’s Hong Kong affairs office warned this month that the city would never be calm unless “black-clad violent protesters” were all removed, describing them as a “political virus” that seeks independence from Beijing.

Beijing blames foreign forces for fomenting unrest and says protesters are undermining the rule of law in Hong Kong.

U.S. Secretary of State Mike Pompeo said on Sunday he believed China had threatened to interfere with the work of U.S. journalists in Hong Kong, and warned Beijing that any decision impinging on Hong Kong’s autonomy could affect the U.S. assessment of Hong Kong’s status.

Britain returned Hong Kong to China in 1997, and the territory was promised a “high degree of autonomy” for 50 years.

The “one country, two systems” deal formed the basis of the territory’s special status under U.S. law, which has helped it thrive as a world financial centre.