Police general Omurbek Suvanaliyev, businessman Omurbek Abdrakhmanov and Adilet Aytikeyev have been in custody since Monday following an interrogation by security officials, ombudsman Tursunbek Akun said. Their leader, former Prime Minister Felix Kulov, was also interrogated but not detained.
Under Kyrgyz law, the three activists from the United Front of Kyrgyzstan face up to eight years in prison for inciting civil unrest.
The United Front, together with the For Reforms movement, protested government policies on the main square of the capital Bishkek April 11-19, when the rally was dispersed using tear gas and stun grenades and injuring 14 people, according to health officials.
The United Front accuses the current President Kurmanbek Bakiyev of failing to improve living standards, curb corruption and introduce democracy in the impoverished Central Asian republic.
Kulov has claimed Bakiyev broke the power-sharing deal that brought them both to office following the so-called "tulip revolution" in 2005, which ousted the longtime leader Askar Akayev, who is currently in exile in Russia.
In the latest wave of protests, the Kulov-led opposition demanded a new Constitution reducing presidential powers and an early general election. The parliament refused to consider it under duress.
