Several people were injured in a brawl that occurred earlier Saturday near the Kyrgyz government building.
The correspondent said the rally participants seized three provokers, beat them and forced them to speak their mind.
"I was given 1,000 soms [$25] for participation in a rally supporting the authorities. My family has nothing to eat, so I agreed," one of those seized said.
Kyrgyz Interior Minister Bolotbek Nogoibayev said the incident will be investigated.
The protesters demand a constitutional reform and early presidential elections.
President Kurmanbek Bakiyev, who came to power in an alliance with Felix Kulov as a result of a violent uprising in 2005, signed fresh constitutional amendments Tuesday consenting to curtail his powers in an apparently futile attempt to prevent a further escalation of the situation.
The former premier Kulov-led opposition accuses the president of failing to improve living standards, curb corruption and introduce democracy to the Central Asian republic. Kulov also argues that part of the votes that brought Bakiyev to presidency belonged to him, which, he said, put in doubt the legitimacy of the president's office.