Organisers and police traded barbs over the slow progress of yesterday's march.
Police accused the Civil Human Rights Front of deliberately making slow progress and warned of possible legal action against the protest organiser, while the front said the police caused a bottleneck by not opening more lanes for the marchers.
While the march was largely peaceful, a high-profile student activist claimed he was pushed to the ground by a police officer, and a policeman was injured in scuffles.
Joshua Wong Chi-fung, of student group Scholarism, said he was pushed to the ground after asking why police were setting up barricades in Yee Wo Street, Causeway Bay.
"I was asking them for an explanation peacefully and was not attempting to push the barricades over," said Wong, whose group was holding an overnight sit-in in Central. "But an officer ordered me to leave the demonstration zone immediately. He then pushed me in the chest and I fell to the ground."
Causeway Bay was a flashpoint in the largely peaceful march. At one point, protesters spilled through the police cordon and into the westbound carriageway close to Sogo. Only one lane was left for traffic.
At 6.40pm, a police officer suffered injuries to his head and midriff, he said, after being pushed to the ground by protesters.
A protester, 22, was arrested nearby for pushing over a barricade that hit a passing bus.
Senior Superintendent Leung Sai-kau, deputy district commander for Wan Chai, said organisers were at fault, and could face legal action for refusing to comply with police instructions.
"The organiser's car that was supposed to head the procession was progressing very slowly and at times it came to a halt. We repeatedly asked the [marchers] to keep moving but we were ignored," Leung said. "The police expressed extreme disappointment with the uncooperative attitude of the organiser."
But front convenor Johnson Yeung Ching-yin blamed the police decision not to close all six lanes of Hennessy Road to traffic to fit in more marchers.
Police ruled out opening all the lanes last week, despite being urged by the Appeal Board on Public Meetings and Processions to make a call on the day.
Instead, protesters had only the three eastbound lanes and partial use of the tram line.
"The police are more interested in pointing fingers than fixing the problem," Yeung said. He said those at the front of the procession stopped because otherwise those at the back would have had no chance of catching up.
"The police simply disrespected the people," he added.
Observers from the Independent Police Complaints Council praised the professionalism of the police, and the marchers for sticking to the law. But the body's new chairman, Larry Kwok Lam-kwong, said "a review may be needed" of how crowd flow could be improved.
Leung said opening more lanes would seriously affect emergency services, public transport and other road users.