Russian opposition politician Aleksei Navalny has rejected sites proposed by the authorities for an anticorruption rally on March 26, vowing to hold the protest in central Moscow.
Navalny's March 22 pledge to conduct the march and demonstration near the Kremlin sets up a possible showdown with police.
Navalny, who helped lead a wave of large antigovernment demonstrations in 2011-12, hopes to bring thousands of people into the streets for a protest against what he says is rampant corruption among officials close to President Vladimir Putin.
The planned rally comes after Navalny's anticorruption group released a report on March 2 accusing Prime Minister Dmitry Medvedev of using charities and NGOs to collect donations from tycoons and state banks and using the funds to buy costly assets.
On March 18, Moscow authorities denied Navalny permission to hold the protest in central Moscow. On March 22, he said the authorities had proposed two alternate sites in less central neighborhoods.
"I'm sorry, but no," Navalny said on his website. He called on people to come out at 2 p.m. Moscow time on March 26 at "any point on Tverskaya Street" -- a main artery that ends outside Red Square and the Kremlin.
Navalny contends that the denial of permission is unlawful and said that if anyone is detained trying to demonstrate on March 26 he will challenge the authorities in court, taking cases as far as the European Court of Human Rights if necessary.
Organizers said on social media that they hope to hold rallies in 98 cities and towns.
Navalny announced in December that he would run for president in a March 2018 election in which Putin, in power as president or prime minister since 1999, is widely expected to seek a new six-year term.
Russian authorities say Navalny will be barred from the ballot if a conviction on financial-crimes charges is upheld on appeal, but he has pushed ahead with campaign-style events.
He has denied any wrongdoing and said his convictions in two separate cases were politically motivated punishment for his opposition to Putin.
