MOSCOW (NewsNation Now) —  A Russian judge Monday ruled that Kremlin critic Alexei Navalny should be held in custody for 30 days until Feb. 15, his spokeswoman said, a day after he was detained upon his arrival in Moscow.

“The court arrested Navalny for 30 days. Until February 15,” Kira Yarmysh, his spokeswoman, wrote on Twitter.

Navalny urged Russians to take to the streets in protest at his treatment in a video clip released after the judge’s ruling.

“Don’t be afraid, take to the streets. Don’t go out for me, go out for yourself and your future,” Navalny said in the video, posted on YouTube.

Navalny was detained at a Moscow airport on Sunday after flying home for the first time since he was poisoned last summer. 

The move drew criticism from Western nations, with calls for new sanctions and for Navalny’s release with Germany’s foreign minister on Monday calling it “incomprehensible.”

The politician’s allies said Monday he was being held at a police precinct outside Moscow and has been refused access to his lawyer. According to Navalny’s lawyers, in an unexpected turn of events, a court hearing into whether Navalny should remain in custody started on Monday at the precinct itself, and they were notified minutes before.

“It is impossible what is happening over here,” Navalny said in video from the improvised court room. “It is lawlessness of the highest degree.”

Navaly accused President Vladimir Putin of throwing the criminal code out of the window in fear.

The Kremlin was expected to comment on his case later on Monday, but usually refers questions about the 44-year-old politician to law enforcement agencies.

Around 200 hundred Navalny supporters gathered outside the police station in below freezing temperatures and demanded he be set free, a Reuters witness said.

State prosecutors asked the court to jail Navalny for 30 days earlier Monday, Ivan Zhdanov, head of Navalny’s ant-corruption foundation, said on Twitter.

Navalny’s detention was widely expected because Russia’s prisons service said he had violated probation terms from a suspended sentence on a 2014 money-laundering conviction.

The prisons service said it would seek to have Navalny serve his 3½-year sentence behind bars.

Four masked police officers detained Navalny at passport control on Sunday evening, the first time he had returned home after being poisoned by what German military tests showed was a Novichok nerve agent, a version of events the Kremlin rejects.

Navalny’s arrest adds another layer of tension to relations between Moscow and the West that have long been strained and were worsened by his poisoning.

The rouble weakened as investors weighed the risk of new sanctions against Moscow.

Calls for Navalny’s immediate release have also come from European Commission President Ursula von der Leyen, the office of the U.N. High Commissioner for Human Rights, British Foreign Secretary Dominic Raab and top officials of other EU nations.

U.S. President-elect Joe Biden’s pick for national security adviser called on Russian authorities to free Navalny. “Mr. Navalny should be immediately released, and the perpetrators of the outrageous attack on his life must be held accountable,” Jake Sullivan tweeted.

The outgoing U.S. secretary of state, Mike Pompeo, said the U.S. “strongly condemns” the decision to arrest Navalny.

Russian Foreign Minister Sergey Lavrov said Monday the stream of reactions to Navalny’s arrest by Western officials reflects an attempt “to divert attention from the crisis of the Western model of development.”

“Navalny’s case has received a foreign policy dimension artificially and without any foundation,” Lavrov said, arguing that his detention was a prerogative of Russian law enforcement agencies that explained their action. “It’s a matter of observing the law,” he added.

Navalny, 44, President Putin’s most prominent and determined foe, brushed off concerns about arrest as he boarded his flight in Berlin on Sunday.

“It’s impossible. I’m an innocent man,” he said.

Navalny fell into a coma while aboard a domestic flight from Siberia to Moscow on Aug. 20. He was transferred from a hospital in Siberia to a Berlin hospital two days later.

Labs in Germany, France and Sweden, and tests by the Organization for the Prohibition of Chemical Weapons, established that he was exposed to a Soviet-era Novichok nerve agent.

Russian authorities insisted that the doctors who treated Navalny in Siberia before he was airlifted to Germany found no traces of poison. Russia refused to open a full-fledged criminal inquiry, citing a lack of evidence that Navalny was poisoned, and officials have challenged Germany to provide proof of the poisoning.

German Foreign Minister Heiko Maas noted that Navalny had returned of his own volition and said “it is completely incomprehensible that he was detained by Russian authorities immediately after his arrival.”

“Russia is bound by its own constitution and by international commitments to the principle of the rule of law and the protection of civil rights,” Maas added. “These principles must of course also be applied to Alexei Navalny. He should be released immediately.”