Image copyright EPA Image caption Students wore facemasks with crosses to protest against China's grip on Hong Kong

An annual pro-democracy protest in Hong Kong saw sweltering heat and one of its lowest turnouts in history on Sunday.

Protesters were marking the 21st anniversary of the former British colony's return to Chinese rule.

Organisers said 50,000 protested, while police said they counted 9,800 at the peak of the march - the lowest recorded by both sides.

Hong Kong's pro-democracy movement has been weakened in the past year, with prominent activists jailed.

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Hong Kong was returned to China in 1997. Under the so-called "one country, two systems" formula, Hong Kong enjoys a high degree of autonomy and certain rights and freedoms not available in mainland China.

Massive demonstrations erupted in 2014 - with tens of thousands camping in the streets. Protesters accused the Chinese government of breaking its promise to allow full democracy in Hong Kong, and of encroaching more and more on the region.

Hundreds of police were deployed on Sunday as demonstrators marched through the streets carrying banners. Some carried yellow umbrellas, a symbol of democratic activism.

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Pro-democracy activist Lui Yuk-lin burned a portrait of Chinese President Xi Jinping.

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The flames were extinguished by security guards.

Image copyright EPA Image caption Hong Kong police officers clear a street near the Sogo department store in Causeway Bay, Hong Kong

Some protesters were pictured wearing Pinocchio masks depicting Hong Kong Chief Executive Carrie Lam, who is seen by activists as a representative of Beijing's interests.

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Pro-democracy activist Joshua Wong, who became famous for his role in the "Umbrella protests" in 2014, spoke to supporters at the march.

Image copyright Reuters

In response to the protest, the government said it had "been following the mottos of 'we care', 'we listen' and 'we act' sincerely".

However, it criticised some of the protest slogans as "sensational and misleading", and said that slogans which did not respect the fact that Hong Kong was part of China were "not in line with Hong Kong's overall interests" and would "undermine" the territory.

Various other causes have become a part of the annual protests, including recycling, environmental issues, and property prices.