Russian authorities have opened a criminal case against a prominent opposition activist and remanded him in pre-trial detention Friday for allegedly spreading “false information” about the country’s armed forces.

A court in Moscow ordered Vladimir Kara-Murza Jr. held in detention until June 12.

Lawyer Vadim Prokhorov told reporters that the false information case against Kara-Murza cited a March 15 speech to the Arizona House of Representatives, in which he denounced the war in Ukraine, as the basis for the latest charges. The activist rejects the accusations.

Russian media reported that similar charges were being drawn up against outspoken tech executive Ilya Krasilshchik, the former publisher of Russia’s top independent news site, Meduza. The moves against the two Kremlin critics are part of a widening crackdown against individuals speaking out against Russia’s war in Ukraine.

Russia adopted a law criminalizing spreading false information about its military shortly after its troops rolled into Ukraine in late February. The offense is punishable by up to 15 years in prison. Human rights advocates so far have counted 32 cases targeting critics of the invasion.

Kara-Murza is a journalist and a former associate of late Russian opposition leader Boris Nemtsov, who was assassinated in 2015, and oligarch-turned-dissident Mikhail Khodorkovsky, who was jailed for years in Russia. Kara-Murza himself was hospitalized with poisoning symptoms twice, in 2015 and 2017.

Arizona Speaker of the House Rusty Bowers denounced the Russian government’s moves against Kara-Murza.

“I am deeply disturbed over news reports regarding the arrest and political persecution of Russian opposition leader Vladimir Kara-Murza,” Bowers said in a statement. “Don’t forget about these freedom fighters, like Vladimir Kara-Murza. We must remember names!”

Arizona Gov. Doug Ducey tweeted: “Kara-Murza’s brave opposition to Putin has inspired us all. Arizona will always stand for freedom. And we will support those like Kara-Murza who take a stand against oppression.”

Krasilshchik, the tech executive who left Russia in early March, told Meduza that he had learnt about the case against him from news reports, which by Friday evening remained unconfirmed. Russian media have linked the charges to an Instagram post, featuring what Krasilshchik said was the photo of charred human remains in the Kyiv suburb of Bucha.

“You can’t recover after seeing the images from Bucha,” the photo caption read. “You feel that the army of this country of ours, it’s capable of anything … and so is the country. That we’re just an order away from mass executions.”

Also Friday, veteran Russian human rights activist Lev Ponomaryov said in an online statement that he was “temporarily” leaving the country.

Ponomaryov, a former State Duma lawmaker who had helped found Russia’s oldest human rights organization in the 1980s, has been a vocal opponent of Russia’s attack on Ukraine, and initiated multiple public petitions against it.

In his statement Friday, he claimed to be “allowing himself to take a vacation” to “look after my health …, but also think through the difficult situation in which we all find ourselves, and plan further (campaigning) activities, which we cannot stop by any means.”

“I doubt my time away will be long,” he added.

In a separate move Friday, the Russian justice ministry added Kara-Murza and several other prominent Kremlin critics to the registry of “foreign agents.” The designation implies additional government scrutiny and carries strong pejorative connotations that can discredit those on the list.

The new additions to the registry included Leonid Volkov, top ally of jailed opposition leader Alexei Navalny, and Alexei Venediktov, former editor-in-chief of Russia’s oldest critical radio station, Ekho Moskvy. The station was taken off the airwaves shortly after Russia invaded Ukraine.