Clashes have broken out at the site of one of Hong Kong's pro-democracy protests as local residents and pro-Beijing supporters tried to evict activists from the street they are occupying.

HONG Kong student leaders have called off talks with the government aimed at bringing an end to mass pro-democracy demonstrations that have paralysed the city, after violent clashes broke out with pro-Beijing crowds at their protest camps.

The Hong Kong Federation of Students made the announcement after pro-government crowds descended on two of their camps, tearing down tents and barricades in what activists said was orchestrated violence by paid thugs from “triad” criminal gangs.

“There is no other option but to call off talks,” the students said in a statement.

“Everybody saw what happened today,” they added. “The government and police turned a blind eye to violent acts by the triads targeting peaceful Occupy protesters”.

The embattled government of Hong Kong leader Leung Chun-ying had promised talks in a bid to end the protests that have brought swathes of the semi-autonomous Chinese city to a standstill since Sunday.

There were angry scenes in the packed Mong Kok and Causeway Bay shopping districts as pro-democracy protesters faced off with large crowds of opponents, with police struggling to keep the situation under control.

But protesters reacted angrily to the lack of arrests, saying pro-Beijing thugs had been freely allowed to attack their camps. The crowds in Mong Kok chanted “Bring out the handcuffs!” late into the night.

Police officers were seen escorting a man from the scene with his faced covered in blood.

There were widespread allegations of sexual assault in the densely-packed crowds, with three girls wearing plastic rain ponchos seen being bundled into a police van in tears after apparently being assaulted at the Causeway Bay protest.

The protesters have massed on the streets in fury at China’s announcement in August that while Hong Kongers can vote for their next leader in 2017, only candidates vetted by Beijing will be able to stand -- a decision dismissed as “fake democracy” by campaigners.

Leung -- seen by the protesters as a Beijing stooge -- refused a demand by protesters to quit but appointed his deputy to sit down with a prominent students’ group at the vanguard of the protests.

Friday’s clashes broke out as the city returned to work after a two-day public holiday.

“Give us Mong Kok back, we Hong Kongers need to eat!” yelled a man removing barricades.

Individuals from both sides pushed and shoved each other as water bottles were thrown, and one anti-Occupy protester chanted: “Beat them to death, good job police!”

Hong Kong Finance Secretary John Tsang warned that if the unrest persists, the city’s status as one of the world’s most important trading hubs could be under threat.

He added that extended protests could seriously dent “confidence in the market system in Hong Kong -- that would bring permanent damage that we could not afford”.

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Police formed cordons and escorted some of the protesters away as hundreds chanted, “Go home!”

The democracy activists linked arms and held hands as they tried to stand their ground against the huge crowd. At one point, police brought in a stretcher to take away a young man, although it was unclear why.

The police themselves were linking arms in an attempt to keep those agitating to get the area cleared of protesters from pushing into their ranks.

The protesters and many onlookers were filming the confrontations; one man tried to grab a video camera from a demonstrator’s hand.

“I would like to appeal to members of the public that they should observe the laws of Hong Kong when they are expressing their views,” police spokesman Steve Hui said when asked about the confrontation in Mong Kok, a working class area far from the main protest site in downtown Hong Kong, the Admiralty area near the territory’s government headquarters.

The latest clashes come after pro-demcracy protesters in Hong Kong clashed with police outside government offices as tensions ran high this morning, despite an eleventh-hour agreement for talks, as China said the demonstrators were “doomed to fail”.

Although most overnight demonstrators had gone home by the morning, more than 100 remained outside the government complex which is now the focal point of protests that have brought parts of the city to a standstill for five days.

Demonstrators are sceptical over what can be gained by the discussions with the government of Chief Executive Leung Chun-ying, which were agreed to late Thursday to defuse escalating tensions as crowds demanded Leung’s resignation.

And today China reiterated its tough stance ahead of the first popular ballot in 2017 to choose the Hong Kong leader, saying there was “no room to make concessions on important principles”.

Police pushed through around 100 demonstrators who were blocking an exit this morning, saying that a seriously ill officer needed to be let out in an ambulance.

In chaotic scenes, protesters refused to move shouting “liar, liar,” in response to the request to move, with police finally forcing their way through to make a path for the ambulance.

Relations between protesters and police have deteriorated since tear gas was fired to disperse crowds last Sunday and boxes carrying rubber bullets were seen being carried by officers on Thursday.

Students vowed to continue their occupation after Leung announced that the government was willing to hold talks with them.

Many are still demanding that the leader step down — and are not impressed by his nomination of his deputy to represent the government in the talks.

“I think he is avoiding people who are voicing their views,” Abigail Hon, 19, told AFP this morning.

“From now on I am going to stay overnight. We hope that Leung can face the problem and respond to what we demand right now,” she said, adding that she wants Leung to speak directly with the students.

The Occupy Central group said it welcomed the talks, adding it hoped they would “provide a turning point in the current political stalemate”.

It was not clear when the talks would start.

Cardinal Zen: We Must Be Courageous The WSJ's Diana Jou speaks to Cardinal Joseph Zen, the former bishop of Hong Kong, about why he supports the pro-democracy protesters.

China hits back

On August 31, China said Hong Kongers would be able to vote for their next chief executive in 2017 but that only candidates vetted by a loyalist committee would be allowed to stand, a decision dismissed as “fake democracy” by campaigners.

Their protests have attracted support from people and politicians around the world.

Huge crowds have shut down central areas of the Chinese city with mass sit-ins all week. Demonstrators had set a midnight Thursday deadline for Leung to quit and for Beijing to guarantee full democracy to the former British colony.

But China has strongly backed Leung and pledged support for police over the protests, which pose a huge challenge to its rule at a time when the Communist Party is cracking down on dissent on the mainland.

In an editorial Friday the People’s Daily, the Communist Party mouthpiece, repeated Beijing’s unbending response.

“Upholding the (August 31) decision of the standing committee of the National People’s Congress is the necessary decision, and the only decision,” it said, adding that the protests are “against legal principles, and doomed to fail”.

Analysts say it is unlikely Leung will step down, in what would be a massive loss of face for Beijing and the Hong Kong establishment.

“If Beijing forces him to resign, they will be seen to be buckling under pressure from the protesters,” said Willy Lam, a China scholar at the Chinese University of Hong Kong.

Authorities have scrubbed mentions of the protests from Chinese social media, while rights groups say more than a dozen activists have been detained on the mainland and as many as 60 others questioned for expressing support for the Hong Kong crowds.

Beijing’s latest comments came after China’s foreign minister issued a stern warning to the United States not to meddle in its “internal affairs”.

China tells the US to back off

International concern continues to grow, with the European Union calling on all sides to remain calm.

“In the light of the ongoing demonstrations, we welcome the restraint shown by both sides. We urge all sides to continue to exercise this restraint,” an EU spokeswoman said on Thursday.

Chris Patten, the last British governor of Hong Kong, welcomed the government’s offer to talk with students, in comments to the BBC.

However, he called Beijing “foolish” for not trusting the people of Hong Kong to elect a suitable candidate to lead the financial hub.

Earlier, China scolded the United States, saying pro-democracy protests sweeping Hong Kong were none of its business and brushing off US calls for restraint, warning it will not tolerate “illegal acts”.

“The Chinese government has very firmly and clearly stated its position. Hong Kong affairs are China’s internal affairs,” Chinese Foreign Minister Wang Yi told US Secretary of State John Kerry on Wednesday ahead of talks at the State Department.

“All countries should respect China’s sovereignty and this is a basic principle of governing international relations,” Mr Wang said sternly.

“I believe for any country, for any society, no one would allow those illegal acts that violate public order. That’s the situation in the United States and that’s the same situation in Hong Kong.”

Mr Kerry however renewed US calls for restraint by the Hong Kong authorities in tackling the protests with huge crowds gathering Wednesday in defiant mood on China’s National Day.

“As China knows, we support universal suffrage in Hong Kong, accordant with the Basic Law,” Mr Kerry told reporters, standing alongside Mr Wang.

“We believe in an open society with the highest possible degree of autonomy and governed by rule of law is essential for Hong Kong’s stability and prosperity,” Mr Kerry said.

“And we have high hopes that the Hong Kong authorities will exercise restraint and respect the protesters right to express their views peacefully.”

Beijing is grappling with one of the biggest challenges to its rule over the city, triggered after it restricted who can run as the commercial hub’s next chief executive.

Mr Wang threw Beijing’s support behind the Hong Kong authorities, saying that they had the “capability to properly handle the current situation in accordance with the law.”