The protesters accuse the police of working with the thugs, who wore masks as they attacked the encampments; the violence has led to postponement of the planned talks between the Umbrella Revolution leaders and the Hong Kong administration.
"The government allowed the mafia to attack peaceful Occupy participants. It has cut off the path to a dialogue, and should be responsible for the consequences," it said.
It was not clear whether the statement reflected the position of other groups involved in the protest.
Occupy Central leader Benny Tai told the BBC they were still only considering a boycott of the talks. However, he said police were not protecting the demonstrators against attacks by their opponents and this situation could not continue.
"It's very, very difficult to maintain any sense of dialogue if the government does not stop these things happening to peaceful protesters," he said.
There was no immediate response from the government to the postponement.
(Image: umbrella revolution_4901, Chet Wong, CC-BY)