Kremlin critic Alexei Navalny said on Friday that Russian prosecutors had asked a court to seize his Moscow apartment as collateral in a lawsuit over opposition protests he helped organize.

Russia’s National Guard, which polices political rallies, wants Navalny and others to pay it 4 million rubles ($62,336) to compensate it for overtime paid to police who worked at a large protest in Moscow this summer, said Navalny.

The National Guard has requested his apartment be seized to make sure he pays, he said, and the Moscow prosecutor’s office has formally asked a court to authorize his flat’s seizure.

The prosecutor’s office did not immediately reply to a request for comment.

Navalny and his allies led political protests this summer over a local election in Moscow that grew into the biggest sustained protest movement in the Russian capital in years, peaking at around 60,000 people before appearing to lose steam.

Moscow’s public and private organizations, as well as Russia’s National Guard, sued the protest leaders for alleged traffic disruptions, lost revenue and overtime pay.

Reports said this week that prosecutors are seeking 5 million rubles ($77,000) from Navalny and his allies to cover fuel costs and salaries for National Guard troops deployed to detain protesters.

Police also sued Navalny and his allies for “damages” in deploying forces during protests, seeking 18 million rubles in compensation.

Reuters contributed reporting to this article.