Alexei Navalny, Russian President Vladimir Putin's leading political opponent, has been detained at his home hours before he was due to take to the streets of Moscow in protest, his wife has revealed.
Navalny's wife Yulia Navalny wrote on Twitter that he had been held at his home by the Russian police but struck a defiant tone, vowing "our plans haven't changed."
In part of his on-going battle against the Kremlin, Navalny had earlier urged Russians to take to the streets Monday in anti-corruption protests. Navalny, who is mounting a long-shot bid to replace President Putin in next year's election, has suffered a series of arrests for his protests against the state. Most recent was in March when he, and up to 1,000 others, were arrested during rallies which aimed to unseat Prime Minister Dmitry Medvedev over corruption concerns.
Despite the events in March, several thousand protesters, including many young people, took to the streets again Monday to rally against the Putin regime.
Protesters were heard chanting "Russia without Putin" and "Russia will be free", according to Reuters reporters on the ground in Moscow.
The same reports cited the arrests of more than 100 people on the streets of Moscow, and dozens more in St. Petersburg.
Navalny had previously received permission from the authorities to stage Monday's protests, which coincide with an official holiday known as Russia Day. However, on Sunday Navalny announced he would be relocating the marches to Moscow's main street near the Kremlin, claiming that the authorities had pressured companies into not providing sound equipment.
The General Prosecutor's Office said prior to the event that protests in this new location would be unlawful, adding that it would take measures to prevent disorder.
The Kremlin has previously denied all allegations of corruption though was not immediately available for comment when contacted by CNBC.