Occupy Central supporters have expressed "outrage" after the police chief accused the pro-democracy organisation of breaking the law with a walk around the city last month.
The walking tour, involving Catholic leader Cardinal Joseph Zen Ze-kiun and other pan-democrats, was intended to promote Occupy's referendum on electoral reform, which drew almost 800,000 votes before it ended on Sunday.
In a letter sent on Wednesday on behalf of police commissioner Andy Tsang Wai-hung, Superintendent Monica Au Yeung Mun-yee told organisers "the number of participants exceeded the legal limit" for public gatherings. The letter "reminded" them that all "public assemblies [and] processions shall comply with Hong Kong statutes".
But Occupy countered that the walk was not a public gathering and therefore needed no police permission. "Andy Tsang ignores the fact that it is a civic right to march and rally. We should be protected under the Basic Law," it said in a statement.
The row came as a new group was launched to oppose Occupy's plans to block streets if the government fails to come up with a plan for political reform that allows a range of candidates to run for chief executive in 2017.
The Alliance for Peace and Democracy, formed yesterday by 38 organisations including four of the city's five leading business chambers, and 28 Beijing-loyalist individuals, will host a two-week petition campaign this month.
The exercise would "allow another aspect of Hongkongers' voices to be heard", said alliance spokesman Robert Chow Yung, who is also convenor of anti-Occupy group Silent Majority.
The petition campaign would be "more transparent" than the Occupy poll conducted by the University of Hong Kong's public opinion programme, Chow said.
He declined to say how that might be achieved, promising more details "in due course".
Meanwhile, the student group that organised Wednesday morning's sit-in on Chater Road vowed to step up action should the government ignore the referendum when it releases its report on electoral reform later this year.
Lester Shum, of the Federation of Students, said a larger blockade of Central would almost certainly be beyond the capability of police to handle.
"If there are 10,000 or more people on Central thoroughfares, police will not be able to clear the areas," Shum said. "The crisis will loom large for the government."
Occupy says the turnout for its vote showed strong support for the idea of allowing the public to nominate candidates in 2017.
Chief Secretary Carrie Lam Cheng Yuet-ngor and other officials say public nomination in any form is unlikely to be included in the reform plan.
The vice-chancellor, Professor Peter Mathieson, told HKU student union president Yvonne Leung Lai-kwok yesterday that he would not offer "blanket support" for arrested students, according to union publication Undergrad. But Mathieson said he respected students' right to free expression and agreed to write in support should Federation of Students secretary general and HKU student Alex Chow Yong-kang be prosecuted.
The Canadian Foreign Ministry also weighed into the debate, with its consulate declaring on Facebook it was "strongly supportive of democratic development in Hong Kong".
The statement was in response to an anti-Occupy advertisement co-signed by the Canadian Chamber of Commerce, which "regrettably" did not notify the consulate before the ad.