Russian officials have stepped up their campaign against jailed Kremlin critic Aleksei Navalny, rounding up his associates and warning social media and news networks against spreading information about nationwide protest this weekend.

At least five allies of the 44-year-old were detained on January 21, including top figures from his Anti-Corruption Foundation (FBK).

The police sweep comes as demonstrations are planned in dozens of cities on January 23 in support of Navalny following his detention last weekend upon his return to Russia from Germany, where he was being treated for a nearly fatal poisoning with a nerve agent since August.

Those detained included Lyubov Sobol, a lawyer and ally of Navalny, Vladlen Los, a lawyer for FBK, Anastasia Panchenko, coordinator of Navalny's headquarters in the southern Krasnodar region, Georgy Alburov, an FBK employee, and Navalny's spokeswoman Kira Yarmysh.

Late in the evening, Sobol walked out of a Moscow police station where she had been held since the morning.

"The Kremlin is having a panic attack. They are ordering that everyone be detained," Sobol told Current Time outside the police station, describing the authorities' behavior as "absolute lawlessness."

Several of those detained have hearings scheduled for January 22, including Yarmysh and Sobol.

Los, who is Belarusian citizen, said he was briefly detained and informed that he must leave Russia by January 25.

SEE ALSO: EU Lawmakers Demand Halt To Nord Stream 2 Over Navalny Arrest

Navalny, President Vladimir Putin's most-prominent critic, was remanded in custody on January 18 for a month in a summary hearing held in a Moscow police station a day after his arrival from Germany.

The court claimed he violated probation requirements in a previous criminal case while receiving life-saving medical treatment in Berlin in a case widely considered trumped up and politically motivated. He faces up to 3 1/2 years in prison.

Navalny has accused Putin of ordering his assassination and has called for Russians to 'take to the streets' to protest against his detention, which has sparked widespread Western condemnation, with the United States, the European Union, France and Canada all calling for his release.

EU lawmakers on January 21 passed a resolution calling on the bloc to 'immediately' stop completion of the Nord Stream 2 pipeline to take Russian natural gas to Germany in response to Navalny's arrest.

Lithuanian Foreign Minister Gabrielius Landsbergis renewed his call for further sanctions on Russia, adding in an interview with RFE/RL that a trip by EU foreign policy chief Josep Borrell to Moscow next month should be cancelled.

Copyright (c) 2018. RFE/RL, Inc. Republished with the permission of Radio Free Europe/Radio Liberty, 1201 Connecticut Ave NW, Ste 400, Washington DC 20036