HONG KONG CITY - Riot police in Hong Kong spent much of Sunday chasing black-clad protesters who held rallies in several of the city's districts in an apparent effort to divide police resources.

Rallies erupted in multiple neighbourhoods with some protesters blocking roads, spraying graffiti on pro-China businesses, smashing windows and erecting barricades.

Police made multiple arrests as they rushed to intercept activists but the clashes were less heavy than earlier this month when the city was virtually shut down by the most intense unrest of the four-month protest movement.

In the Kowloon area of Mongkok, riot police burst from an unmarked van that had screeched up to a blockade made of bamboo scaffolding poles and quickly chased and detained multiple protesters.

In Tai Po, in the New Territories, officers charged into a shopping centre and made at least two arrests after demonstrators tagged several businesses with slogans.

Similar flashmobs and brief clashes were witnessed in at least three other locations with bystanders often heckling police as they made arrests.

The protests started in opposition to a now-abandoned extradition bill, under which residents would have been sent to Communist-controlled mainland courts. They have widened into a pro-democracy movement and also an outlet for anger at social inequality in the city, which boasts some of the world's most expensive real estate.

The unrest has plunged Hong Kong into its worst crisis since Britain handed it back to China in 1997 and poses the biggest popular challenge to Chinese President Xi Jinping since he came to power in 2012.

Protesters believe China has been eroding Hong Kong's freedoms, guaranteed under a "one country, two systems" formula introduced with the 1997 handover.

China denies the accusation and says foreign countries, including Britain and the United States, are fomenting unrest.

On Sunday, hundreds of protesters wearing face masks staged a peaceful march in Kowloon, with only a small group trashing shops and mainland China banks.

The government said petrol bombs were thrown into the entrance of the Kowloon Tong station and a Kowloon government office was set on fire.

Riot police were deployed to the streets but the demonstrators had dispersed without any major confrontation by late on Sunday night.

The Hong Kong government introduced colonial-era emergency laws last week to ban the wearing of face masks at public rallies, a move that sparked some of the worst violence since the unrest started in June.

Police have arrested more than 2,300 people since the protests began. Since September, nearly 40 percent of those arrested were under the age of 18 and a tenth were under 15, Reuters news agency reported.

The protesters also accuse police of using excessive force, claims they deny. Two protesters have been shot and wounded during the skirmishes over the past four months.(FA)