The opposition accuses President Kurmanbek Bakiyev and his government of failing to deliver on promises to crack down on corruption and raise living standards in the impoverished ex-Soviet republic since coming to power in 2005.
"We will continue [protests] until the authorities fulfill our demands, or the ruling pair [the president and Prime Minister Felix Kulov] resign," said Almazbek Atambayev, leader of the opposition For Reform movement.
The rally was launched earlier Thursday after the president backtracked on an agreement reached earlier in the week to give parliament a greater say in running the Central Asian state, explaining that time was needed to discuss corresponding amendments to the Constitution.
"You have seen how many people have taken to the [central] square, you have seen their sentiments. Of course the authorities will now have to think," Atambayev said.
He said opposition supporters will not resort to violence during the night, and that more protesters will come to the square tomorrow.
Security has been tightened in Bishkek for fear of a new outbreak of violence, with hundreds of riot police on duty. But Deputy Interior Minister Sherkoza Myrzakarimov assured that police "will not intervene as long as protesters comply with the law."
