Protesters arrested in Tuesday night's standoff accused police of acting with a political motive, with two lawmakers saying the crowd had already dispersed when they were taken away.
League of Social Democrats' "Long Hair" Leung Kwok-hung said he was alone, and surrounded by hundreds of police, for about half an hour before he was arrested.
No warning was given before the arrest was made, he said.
People Power's Albert Chan Wai-yip said he was walking to the Legislative Council to drop off something at his office when he was approached by police and taken away.
He said the stand-off was already over at that time.
They were two of nine protesters arrested for violation of public order and unlawful assembly in the stand-off.
The others included League member "The Bull" Tsang Kin-shing and former radio host "Fast Beat" Tam Tak-chi.
Leung said the police had surrounded about 100 protesters in a square at the junction of Pedder Street and De Voeux Road Central for over an hour.
Eventually all of the other protesters left the square, leaving Leung on his own. He continued to chant slogans and was arrested without warning when he went to pick up a bottle of water on the roadside, he said.
"It's ridiculous," Leung said. "How would an ordinary person know they were about to be arrested?"
Tsang and Chan also described the police action as "political arrests".
Independent Police Complaints Council secretary general Ricky Chu Man-kin said he believed the traffic was held up on Garden Road and Upper Albert Road because negotiations had broken down between protesters and police, who would not let the crowd gather in front of Government House.
He said the council would seek further clarification from police on the matter.
He also said the conduct of both police and protesters during the anti-government rally was satisfactory, in terms of distribution of fundraising stalls along the route.