Friction between pro-democracy protesters and opponents of their weeklong occupation of major Hong Kong streets persisted Saturday as police denied any connection to criminal gangs suspected of inciting attacks on largely peaceful demonstrators.

Police arrested 19 people during a night of running brawls in which at least 12 people and six officers were injured. Eight men were believed to have backgrounds linked to triads, or organized crime, said Senior Superintendent Patrick Kwok Pak-chung.

Officials vehemently denied rumors they might have coordinated with the gangs to clear the streets.

"Such rumors linking us to 'black societies,' are utterly unfair," visibly agitated Hong Kong's security chief, Lai Tung-kwok, told reporters.

The confrontations, mostly in gritty, blue-collar Mong Kok district, led protest leaders to call off planned talks with the government on political reforms. Students and other activists are protesting China's decision to require a committee of mostly pro-Beijing figures screen candidates for the city's first-ever election of its top leader. They are also demanding the resignation of the current chief executive, Leung Chun-ying.

With the talks suspended, the next steps in the crisis were uncertain. Police have repeatedly urged protesters and their opponents to clear the streets for the sake of public order, but have shown toleration after the earlier attempt to disperse the protesters just drew more people into the streets.

The standoff in Mong Kok, across Victoria Harbor from the activists' main protest encampment, continued Saturday after a tense night when hundreds of supporters of the protesters gathered to protect them.

Kwok said those arrested were facing charges of unlawful assembly, fighting in public and assault. On Saturday, the situation remained tense as the anti-protest groups regrouped in Mong Kok, at times chanting "Pack Up!" at the protesters.

The opponents of the demonstrations are using blue ribbons to signal their support for the mainland Chinese government, while the protesters are wearing yellow ribbons. Some of those belonging to the "blue ribbon" side staged a rally in Kowloon's waterfront Tsim Sha Tsui.

"Love Hong Kong" and "Support Police" they chanted, holding up flags and heart-shaped signs with the slogan, "Alliance in support of our police force."

Early Saturday, the Hong Kong Federation of Students, one of the groups leading the demonstrations that drew tens of thousands of people earlier this week, said they saw no choice but to cancel the dialogue they had agreed to after Leung proposed talks. They demanded the government hold someone responsible for the scuffles Friday, the worst disturbances since police used tear gas and pepper spray to try to disperse the protesters the weekend before.

The allegations that organized crime members were involved in the clashes fueled jitters Saturday at the movement's main camp, on a highway outside government headquarters. There were frequent calls for supporters to rush to barricades after sporadic rumors that people were coming to attack them.

"Many people are gathering here and they are very determined to unite against the triad members," said Amy Ho, 21, who was studying translation at university.

On social media, an image circulated purportedly calling on people in the "silent majority" to gather and agitate the protesters in Mong Kok for 300 Hong Kong dollars ($38), promising bonuses for extra destruction. The information could not be verified and calls to a mobile phone number listed on the notice did not go through. Protesters also accused police of working together with triads to use force to attack them, but police denied it.

At least some of those opposed to protesters were residents fed up with the inconvenience of blocked streets and closed shops.

The protesters have been in the streets since Sept. 26, pledging to preserve Hong Kong's Western-style legal system and civil liberties. They want the Chinese government to reverse a decision requiring all candidates in the first election for Hong Kong's leader in 2017 to be approved by a mostly pro-Beijing committee. The demonstrators want open nominations.

China's government has mostly kept quiet during the crisis, other than to harshly criticize the protests and support the Hong Kong government's efforts to disperse them.

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Associated Press writers Joanna Chiu and Wendy Tang contributed to this report.