Clashes broke out on Sunday as police moved to disperse some activists in Hong Kong. (FILE)

Police arrested six people during a demonstration in one of Hong Kong's most popular tourist areas on Sunday, where thousands of protesters sought to raise awareness among mainland Chinese visitors about the political crisis that has rocked the city.

Protest organisers said 230,000 people marched through the streets of Kowloon, across the harbour from Hong Kong's Central business district, in the latest wave of demonstrations against an extradition bill that would allow people to be sent to mainland China to face trial.

Police put the number at 56,000 at its peak.

Chinese censors have worked hard to erase or block news of Hong Kong's biggest and most violent protests in decades amid fears they could inspire demonstrations on the mainland.

Hong Kong's embattled leader Carrie Lam suspended the extradition bill after violent protests last month when police fired rubber bullets and tear gas, but she has rejected calls to scrap it.

Protests over the bill have now morphed into calls for Lam to step down, investigations over what some describe as excessive police force and greater democracy.

Hong Kong has been governed under a "one country, two systems" formula since its return from British to Chinese rule in 1997, allowing freedoms not enjoyed in mainland China, including the right to protest and an independent judiciary.

Critics say the extradition law could threaten Hong Kong's rule of law and its international reputation as an Asian financial hub. Some Hong Kong tycoons have already started moving personal wealth offshore.

Clashes broke out on Sunday as police moved to disperse some activists after they blocked roads following the largely peaceful protest over the bill that has plunged the former British colony into political turmoil.

On July 1, the anniversary of Hong Kong's return to Chinese rule, protesters besieged and ransacked the legislative building in the heart of the city before being driven back by police firing tear gas.