Russian authorities raided homes and offices belonging to supporters of Kremlin opposition leader Alexei Navalny in 43 cities on Thursday, a move Navalny claimed was the “biggest police operation in modern Russian history.”

More than 200 raids have taken place across Russia, from Vladivostok on the Pacific to Krasnodar in Russia's southwest, as part of an investigation into supposed money laundering, Navalny said.

"We are not going to stop our work, don't you worry about that," Navalny said in a video message in which he mocked authorities for the raids, comparing them to a crackdown on a drug cartel.

“Putin is very angry and is stamping his feet,” Navalny said, a reference to the ruling United Russia – which supports President Vladimir Putin – recently losing a third of its seats in the Moscow city assembly. “I congratulate you. Today the biggest police operation in modern Russian history is taking place.”

Police appeared to be targeting people who were part of Navalny's 2018 presidential election campaign. Though Navalny was barred from running, his supporters in local election headquarters in dozens of Russian cities have grown in number and in force, investigating high-level corruption and mobilizing supporters for opposition rallies.

Many of Navalny's allies ran in local elections last Sunday and monitored the voting, documenting what they said were widespread violations.

"We're obviously talking about an attempt to hamper the operations of our regional network," Navalny supporter Leonid Volkov told The Associated Press.

Volkov said he expected the police to confiscate equipment and described the raids as a "robbery attempt," estimating the damage at $15,000.

Despite the vast time differences across the country, authorities turned up at all of Navalny's chapters at 6 a.m. Moscow time, which points to a coordinated effort, Volkov said.

PUTIN AGAIN THREATENS TO DEVELOP PREVIOUSLY BANNED MISSILES IF US DOES

Election monitoring group Golos reported that homes of three of its regional coordinators had been raided. It said in a statement that the three people were training election monitors before the Sunday vote.

CLICK HERE TO GET THE FOX NEWS APP

Golos condemned the police actions as "an attempt of pressure and intimidation of public monitors."

The Associated Press contributed to this report.