Russian authorities blamed Ukrainian intelligence agencies on Monday for orchestrating a bombing at a St. Petersburg cafe that killed a Russian military blogger who fervently supported Moscow’s invasion of Ukraine, and they arrested a suspect.

Ukrainian authorities did not directly respond to the accusation, but President Volodymyr Zelenskyy said in reference to the attack that he doesn't think about events in Russia, and a senior Ukrainian official earlier described the bombing as part of Russia's internal turmoil.

Vladlen Tatarsky, 40, was killed Sunday as he led a discussion at the cafe on the banks of the Neva River in the historic heart of Russia's second-largest city, officials said. Tatarsky, who had filed regular reports from the front lines in Ukraine, was the pen name for Maxim Fomin. He had accumulated more than 560,000 followers on his Telegram messaging app channel.

The bombing, which also wounded more than 30 other people, was the latest attack inside Russia on a high-profile pro-war figure. Last year, a nationalist TV commentator was assassinated when a bomb exploded in her SUV outside Moscow.

Investigators said they believe the bomb at the cafe was hidden in a bust of Tatarsky that a member of the audience gave him just before the explosion. A video showed him joking as he removed a wrapper to reveal the gold-colored bust of a man wearing a helmet, “What a handsome guy!”

Russian authorities announced the arrest of Darya Trepova, a 26-year-old St. Petersburg resident seen on video presenting Tatarsky with the bust, and classified the case as an act of terrorism. Police had detained Trepova for participating in a rally against the war on Feb. 24, 2022, the day of the invasion, and she spent 10 days in jail.

Designating the case as a terrorist act gives authorities more power to pursue their investigation, increases the maximum punishment and limits the rights of suspects.

The Interior Ministry released a video showing Trepova telling a police officer that she brought the statuette that exploded to the cafe. When asked who gave it to her, she said she would explain it later. The circumstances under which Trepova spoke were unclear, including whether she was under duress.

According to Russian media reports, Trepova told investigators she was asked to deliver the bust, but didn’t know what was inside it.

The National Anti-Terrorist Committee, which coordinates counter-terrorism operations, said the bombing was “planned by Ukrainian special services,” noting Trepova was an “active supporter” of imprisoned Russian opposition leader Alexei Navalny.

Navalny, the Kremlin's fiercest foe who had exposed official corruption and organized massive anti-government protests, is serving a nine-year fraud sentence that he has denounced as a political vendetta.

Navalny associate Ivan Zhdanov warned that authorities could use the claim of involvement by political opponents as a pretext to extend his prison term. He also charged that Russian security agencies could be behind the explosion to cast Navalny's supporters as an "internal enemy.”

According to Russian media reports, police tracked down Trepova using surveillance cameras, although she reportedly cut her long blond hair short to change her look and moved to a different apartment in an apparent attempt to escape.

Military bloggers and patriotic commentators compared the bombing to the August 2022 assassination of nationalist TV commentator Darya Dugina , who was killed when a remote-controlled explosive planted in her SUV blew up as she drove on the outskirts of Moscow.

Russian authorities blamed Ukraine’s military intelligence for Dugina’s death, but Kyiv denied involvement.

Kremlin spokesman Dmitry Peskov said the attacks on Dugina and Tatarsky proved that Moscow was justified in launching what it describes as “the special military operation" in Ukraine.

Moscow has offered a series of explanations for the invasion, denounced by Ukraine and the West as an unprovoked act of aggression, while providing little if any evidence for the charges.

“Russia has faced the Kyiv regime, which has supported terrorist activities,” Peskov said in a conference call with reporters. “That is why the special military operation is being conducted.”

Yevgeny Prigozhin, the St. Petersburg millionaire restaurateur who heads the Wagner Group military contractor spearheading Moscow’s offensive in eastern Ukraine, said he owned the cafe and allowed patriotic groups to use it for meetings. He said he doubts the involvement of Ukrainian authorities in the bombing, saying it was likely launched by a “group of radicals” unrelated to the government in Kyiv.

Zelenskyy brushed off questions about the bombing.

“I don’t think about what is happening in St. Petersburg or Moscow. Russia should think about this. I am thinking about our country,” Zelenskyy told journalists.

While not claiming responsibility for various explosions, bombings and other attacks within Russia since the invasion began, Ukrainian authorities have often greeted them jubilantly and insisted on Ukraine’s right to launch such assaults.

Ukrainian presidential adviser Mykhailo Podolyak responded to the news of the bombing by casting it as a result of infighting in Russia.

“Spiders are eating each other in a jar,” he tweeted in English late Sunday. “Question of when domestic terrorism would become an instrument of internal political fight was a matter of time.”

On Monday, Podolyak said Russia has “returned to the Soviet classics,” pointing to its increasing isolation, the rise of espionage cases and an increase in political repression .

Last week, Russia’s security service announced the arrest of American reporter Evan Gershkovich on spying charges, the first time a U.S. correspondent has been detained on such accusations since the Cold War. His newspaper, The Wall Street Journal, has vehemently rejected the allegations and demanded his release.

Tatarsky was born in Ukraine's industrial heartland of the Donbas and worked as a coal miner before starting a furniture trade business. When he ran into financial difficulties, he robbed a bank and was sentenced to prison.

He fled custody after a Russia-backed separatist rebellion engulfed the Donbas in 2014, weeks after Moscow’s illegal annexation of Ukraine’s Crimean Peninsula. Then he joined separatist rebels and fought on the front line before turning to blogging.

While Russian authorities have silenced alternative voices by shutting down independent news outlets critical of the war and jailing critics of President Vladimir Putin, military bloggers have played an increasingly visible role. While strongly supporting the war, they also have frequently pointed out flaws in Russian military strategy and occasionally criticized the military brass.

Putin saluted Tatarsky posthumously Monday with a bravery award.