China reiterated on Monday its support for Hong Kong's leader, Carrie Lam (above), and its police, and called on Hong Kong people to oppose violence following another weekend of clashes between protesters and police in the city.

Hong Kong bore the scars on Monday of its eighth straight weekend of violent protests, with hard hats, umbrellas and water bottles littering some central streets.

Millions have taken part in street protests against a now-suspended extradition bill that would have allowed criminal suspects in Hong Kong to be sent to China to face trial in Communist Party-controlled courts.

The protests have at times paralysed parts of the financial district, shut government offices and disrupted business operations across the city. Officials have also warned about the impact of the unrest on Hong Kong’s economy.

Beijing has stood by the city's pro-Beijing leader Lam, and the Chinese government's Hong Kong and Macau Affairs Office, which has cabinet-level authority over the former British colony, reiterated that support at a news conference in Beijing on Monday.

"The central government firmly supports Lam leading the Hong Kong government’s administration according to law, firmly supports the Hong Kong police strictly enforcing rule of law," Yang Guang, a spokesperson for the office, told a news conference.

The most important thing was for Hong Kong to handle the unrest according to the law, Yang said, blaming irresponsible figures in the West for stirring up the trouble in a bid to contain China's development.

Such efforts would fail, he said.

Asked under what conditions the People's Liberation Army could intervene, Yang referred as other officials have done, to Hong Kong's mini-constitution, known as the basic law, which states that the Hong Kong government can ask the PLA garrison in the city to help maintain order.

Legal scholars have described that as a high threshold.

Yang said Hong Kong's government and society needed to come up with more effective ways to help young people address concerns over housing, employment and other issues, although officials did not announce any specific measures to address the unrest.

The past weekend saw more clashes between protesters and police, who again fired rubber bullets and tear gas as the demonstrations grow increasingly violent.

Police sought to defend China's main representative office in Hong Kong from protesters on Sunday for the second consecutive weekend, with the building near the heart of the city fortified with barricades.

Police said they had arrested at least 49 people over Sunday's protests for offences including unauthorised assembly and possession of offensive weapons.

Pessimistic

The protests are the most serious political crisis in Hong Kong since it returned to China 22 years ago.

They also pose the greatest popular challenge to Chinese leader Xi Jinping since he came to power in 2012.

Hong Kong returned from British to Chinese rule in 1997 under a "one country, two systems" formula that promised wide-ranging freedoms denied to citizens in mainland China.

Many fear Beijing is increasingly chipping away at those freedoms.

What began as a movement to oppose the extradition law has taken on broader demands. They include the resignation of Hong Kong's Beijing-backed leader Lam, calls for full democracy and an independent inquiry into what some say has been excessive force used by police against protesters.

Lam has refused to accede to any of the demands.

The American Chamber of Commerce in Hong Kong said on Monday that, according to a recent survey, international businesses were pessimistic about the short-term prospects for the city due to escalating violence and political deadlock.

Respondents reported a deepening perception within their companies and among overseas customers that Hong Kong had become less safe and a riskier place in which to conduct business, it said.

A series of protests are planned over coming weeks and the outlook is increasingly uncertain.

Labour Party lawmaker Fernando Cheung, who has tried to mediate between activists and police, told Reuters Lam needed to heed demands to withdraw the extradition bill and set up an independent commission, among other requests.

"Short of that, we would only be spiralling down towards even more violence, death, a curfew and even PLA interference," Cheung said.