President Xi Jinping is scheduled to attend celebrations marking the 20th anniversary of Hong Kong’s return from British to Chinese rule.

He will also preside over the swearing-in ceremony for Hong Kong’s new leader.

Before the handover of the former British colony, China’s leaders agreed to govern the city under a One country, Two systems formula.

This gave Hong Kong its own legal system, limited democracy with multiple political parties, and rights such as freedom of assembly and free speech.

But now there are signs that some of those freedoms are under threat.

Al Jazeera’s Adrian Brown reports from Hong Kong.