Police in Moscow detained prominent anti-Kremlin activist Ildar Dadin on Friday — less than two weeks after he was released from prison — when he staged a one-man demonstration outside Russia's prison service.

Dadin, 34, was freed from a Siberian prison last month after becoming the first person to be jailed under new rules that made some forms of non-violent protest a criminal offense.

He was sentenced to three years in prison — reduced to two and a half on appeal — in December 2015 for a series of peaceful one-man protests against the Kremlin. The Supreme Court quashed his conviction on Feb. 22.