HONG KONG - Hong Kong pro-democracy activists staged a cat-and-mouse game with riot police on Sunday, mounting protests in several shopping malls and chanting slogans such as "Free Hong Kong" until police arrived and then dispersing among weekend shoppers.

Some protesters vandalized shops and police made several arrests but in most cases the protests were peaceful. The young protesters, many wearing face masks, were often supported by Sunday shoppers out for lunch.

In one incident, a group of 50 shoppers inside a mall, none wearing masks, faced off against riot police outside the mall doors, chanting "Hong Kong police mafia". The shoppers cheered and clapped when police drove off.

Hong Kong's police, once praised as "Asia's finest", have been accused of using excessive force in dealing with protesters and have lost the confidence and respect of many Hong Kongers.

"Police officers have used minimum necessary force to disperse protesters, including the deployment of tear gas. We warn the rioters to stop their illegal acts immediately," police said in a statement on Sunday.

Hong Kong has been battered by four months of often massive and violent protests against what is seen as Beijing's tightening grip on the Chinese-ruled city, and more protests are planned for Sunday.

The protests started in opposition to a now-abandoned extradition bill but have widened into a pro-democracy movement and 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 the city 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.

"Hong Kong used to be a prosperous city and now she has become a police state. Hong Kong is my home. We should protect her. We should resist," said a 70-year-old who only gave his last name, Hui.

He was part of a group of 60- to 70-year-olds on Nathan Road, Kowloon, cheering the protesters, urging them to block the road and warning them when police were returning.

Riot police entered some malls and metro stations and marched down roads in a show of force as protesters erected makeshift road barriers. Police made several arrests, chasing down individual protesters in the street.

"I think the police have been using their power to suppress the citizens. That’s why more and more young children come out and protest against the government and the police. Those being arrested don’t have human rights. This is not fair," said resident Mary Lam, 26.

Petrol bombs were thrown inside a Hong Kong metro rail station on Saturday but no one was injured, the government said. -Reuters