Hong Kong talks have been called off following violent clashes between supporters of Chinese rule and pro-democracy protesters.
There were clashes at two pro-democracy camps in the packed Mong Kok and Causeway Bay districts after hundreds of pro-China supporters tore down their tents and barricades and threw water bottles.
The "Occupy" activists accused the government and police of turning a blind eye to "violent acts" by their opponents.
In Mong Kok, protest leaders had urged their supporters to leave for their own safety but hundreds ignored the plea and descended on the area to outnumber the counter-protesters.
Officers formed a human chain to keep the two groups apart, with some pro-democracy protesters reportedly throwing objects as some members of the pro-China group were led away by bus.
The scuffles were the most chaotic since police used tear gas and pepper spray last weekend to try to disperse protesters pushing for greater electoral reforms for the territory.
The protests are the biggest challenge to China's authority since Britain handed control of Hong Kong to Beijing in 1997.
The embattled government of Hong Kong leader Leung Chun-ying had promised talks in an attempt to end the demonstrations that have brought large parts of the semi-autonomous Chinese city to a standstill since Sunday.
Tens of thousands of people have filled major roads demanding China grants them free and fair elections in 2017 after Beijing said only vetted candidates could run.
The Hong Kong Federation of Students said in a statement: "There is no other option but to call off talks. Everybody saw what happened today.
"The government and police turned a blind eye to violent acts by the triads targeting peaceful Occupy protesters".
Police said there had been at least two arrests and defended their response to the chaotic scenes, with senior superintendent Kong Man-keung telling reporters the force had "deployed a lot of manpower to control the situation".
Protesters reacted angrily to the 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.
The pro-Beijing supporters were said to be visibly older than the pro-democracy group and yelled, shoved and tried to drag the younger protesters away.
Many shouted their anger that the demonstrators were preventing them from going to work and earning a living.
"Give us Mong Kok back, we Hong Kongers need to eat!" one man shouted as he attempted to remove the barricades.
One young female protester said: "We're sorry for the inconvenient cause but we hope you can show consideration."
She said she was determined to stay, adding: "Yes I do (have safety worries) but I don't have other choice."
A woman on the other side said: "My father lives here and I come here to buy things but the shops are closed and the roads are closed and everybody cannot go to work.
"I completely respect their rights to express their views but I just think Hong Kong is not such a place where you have to occupy roads or create such a tension between people to express their views."
