Kremlin critic Alexei Navalny said on Monday he would no longer comply with the terms of his house arrest and had cut off his monitoring tag.
Navalny, 38, who led mass protests against Putin three years ago, was handed a suspended sentence on December 30 after being found guilty of embezzling money in a trial that led to his brother being jailed on similar charges.
He was placed under house arrest almost a year ago during the investigation but said in a blog that he was perhaps the only person in Russian legal history to be kept under house arrest after being sentenced.
Navalny said he should have been released after sentencing in late December, but instead was being held, pending publication of the verdict on January 15 - a situation that even the police did not know how to deal with.
"It is stupid to brag, but I am the first person in the history of Russian courts to be sitting under house arrest after the verdict," he said on his blog.
"I refuse to comply with the requirements of my illegal detention under house arrest. The bracelet with some effort has been cut off with kitchen scissors," Navalny wrote, alongside a picture of the bracelet, or tag, that monitors his movements.
He said he had no plans to travel far.
When Navalny was handed his suspended sentence, his brother Oleg, 31, was jailed for three and a half years.
They had faced charges of stealing 30 million rubles, around $500,000 at the current exchange rate, from two firms including an affiliate of French cosmetics company Yves Rocher between 2008 and 2012.
Opposition figures said jailing Alexei Navalny risked new protests so he was being punished through his brother instead. The Kremlin denies influencing court decisions.
After the sentencing, Alexei Navalny broke house arrest to join a rally of hundreds of his supporters outside the Kremlin but was swiftly detained and driven home by police.
Alexei Navalny led the mass demonstrations in the winter of 2011-12 that at times brought tens of thousands of people on to the streets of Moscow and several other big Russian cities to protest against corruption and alleged election fraud.