Rights watchers said the response by the police was a particularly vivid example of the country’s restrictions on free speech.
Mr. Sagutdinov’s encounter with the police in the city of Uralsk on Monday, which was filmed and posted on YouTube, came as the country prepares for a presidential election in June, its first transfer of power in decades.
“I want to show that the idiocy in our country has gotten so strong that the police will detain me now even though there are no inscriptions, no slogans, without my chanting or saying anything,” Mr. Sagutdinov said in the video.
The video spread rapidly in the local news media and on social media, and some people posted photos of themselves holding blank signs in support.
On Tuesday, a police statement offered an account of events on Monday in which the authorities received a report of an unknown male standing in the square, holding a placard, with a crowd growing around him. He was detained but released a short time later.
The police statement maintained that the authorities “were acting within the boundaries of the law.”
