World Bulletin / News Desk
Citing the police, TASS said Navalny was detained after calling to change the anti-Kremlin demonstration area from approved Sakharov Avenue to "unauthorized" Tverskaya Street in the capital of Moscow.
He had called for mass protests in the capital and other cities against what he said a corrupt system of rule.
Navalny, the founder of the Anti-Corruption Foundation and chairman of Russia’s opposition Progress Party, tweeted earlier on Monday that they will "peacefully" gather at Tverskaya Street.
However, Moscow Prosecutor's Office warned against holding an "unauthorized action" on Tverskaya Street, according to TASS.
It said any attempt on Tverskaya Street will be a "direct violation" of the law.
The police strengthened security measures at the street, according to TASS.
On March, Russian police detained more than 500 people during protests -- led by Navalny -- which took place in several cities including Moscow and St. Petersburg.