HONG KONG (REUTERS) - Beijing supports more bold measures to tackle the roots of unrest that has roiled Hong Kong for months, a senior Chinese official said on Wednesday (Nov 6), just hours after a knife-wielding man attacked a pro-Beijing lawmaker in the financial hub.

Mr Han Zheng, China's Vice-Premier, at an official meeting with Hong Kong's embattled leader Carrie Lam in Beijing, said that anti-government protests were damaging the "one country, two systems" framework under which the city has been governed since its handover from Britain to Beijing in 1997.

"We firmly support the Special Administrative Region government to adopt more pro-active and more effective measures to solve the social problems," Vice-Premier Han said, as he sat next to Mrs Lam in a meeting room in the Diaoyutai State Guesthouse.

Mr Han said the social problems included unaffordable housing in the city, which is classified as a special region of China.

China's Communist Party said on Tuesday it would not tolerate any "separatist behaviour" after some protesters called for independence. Mr Han said the violence had exceeded the "bottom line" of the rule law and of morality.

What started as agitation against a now-scrapped extradition Bill that would have allowed people to be sent to mainland China for trial, has widened into calls for full democracy, among other demands.

The more than five months of protests have plunged Hong Kong into its biggest political crisis in decades and pose one of the gravest challenges to Chinese President Xi Jinping's rule since he came to power in 2012.

Mr Han was meeting Mrs Lam just hours after a man stabbed pro-Beijing lawmaker Junius Ho in the chest with a knife, the latest incident in a series of attacks on candidates running in the city's district council elections.

Both pro-democratic and pro-establishment figures have been targeted. The vote is on Nov 24.

The alleged attacker was subdued and arrested. Mr Ho said in a statement posted online that he had suffered a knife wound to the upper left part of his chest, but said his life was not at risk. Two of his colleagues were also hurt, he said.

The attacker's motive was not known but Mr Ho gained notoriety among anti-government protesters in July when he was filmed laughing and shaking hands with suspected triad gang members who assaulted young demonstrators.

An online video showed the assailant handing Mr Ho a bunch of yellow flowers, before taking a weapon out of his bag and stabbing him.

Mrs Lam strongly condemned the attack when she met reporters in Beijing.

Among the prominent people to be attacked during the months of sometimes violent unrest was Mr Jimmy Sham, a leader of Hong Kong's Civil Human Rights Front, which organised mass rallies against the extradition Bill. He was attacked in October.

District councillor Andrew Chiu was assaulted by a man who bit off part of his ear outside a shopping mall this week.

Further protests are planned on Wednesday at some of Hong Kong's universities, activists said. Police fired water cannons to disperse protesters at a Guy Fawkes-themed march on Tuesday night.

Protesters are demanding an end to perceived Chinese meddling in the territory's affairs, as well as universal suffrage and an independent inquiry into alleged police brutality, among other demands.

Beijing denies interfering and blames foreign governments for fuelling the unrest.

President Xi met Mrs Lam on Tuesday in Shanghai, vouching support for her administration.

Following the meeting, Mrs Lam denied rumours that the government was considering an amnesty for protesters charged with offences.

Hundreds of black-clad students, meanwhile, protested against perceived police brutality and called for an investigation into injuries suffered by a student from the Hong Kong University of Science and Technology fighting for his life after falling one floor in a car park.

The student fell from the third to the second floor of the parking lot in Tseung Kwan O, in the east of the Kowloon peninsula, during crowd dispersal operations at the weekend and was in critical condition, hospital authorities said.

University president Wei Shyy said he had visited the 22-year-old student and his parents.

"I personally feel the mood of our citizens, by and large, has worsened because of frustration, disagreement and because many feel despair," he told angry students demanding to know what had happened.

He said the university had sent a letter to the police, asking for guidelines of how they use tear gas.

There have been conflicting accounts of how the student fell. Some have also accused police of blocking an ambulance trying to reach him.

Police said they were not firing tear gas at the estimated time of his fall but did not rule out that he could have been trying to flee tear gas. They denied blocking an ambulance.

"I have known him for one year," said student James, 22."...He's a quiet person. We play basketball together. I am worried about him. I hope he can wake up."