As protesters dispersed after calling for political reform in their oil-rich country, Kazakh police were still holding several key opposition leaders who'd been detained as they left their homes for the rally, RFE/RL's Kazakh Service reports.
The leaders apparently remained at local police stations.
The protesters were blocked by police from demonstrating in Almaty's main square, but assembled along a nearby road for the rally.
Detainees in the hours before the event included Bulat Abilov and Zharmakhan Tuyakbai, co-chairmen of the opposition Azat party, along with the party's secretary general, Amirzhan Kosanov.
There also were reports of some protesters at the rally being dragged into police vans.
One unidentified protest speaker was pulled off the stage by police as he tried to address the crowd.
"Why is Nazarbaev still insatiable?" the man said. "Nazarbaev, go! If we keep silent, our history will not forgive us."
Smaller, related protests were held in some other Kazakh cities.
Just 20 or so people gathered in the capital, Astana.
A handful of wives of arrested oil workers gathered in the tense western Kazah city of Zhanaozen to call for their release, where a clash with police in December led to at least 17 deaths. Raids and arrests followed, including of civic leaders trying to investigate the circumstances of the December 16 bloodshed and several police officers.
Kazakhstan's opposition had called for people across the country to join public calls to release several opposition figures detained earlier this month and for fair elections, an independent and impartial judiciary, and freedom of speech.
President Nursultan Nazarbaev's government is a frequent object of international criticism for its human rights policies and authoritarian record whose selection to chair the Organization for Security and Cooperation in Europe in 2010 sparked heated debate.