MOSCOW - Russia on Monday accused Ukraine of organising the murder of a prominent war blogger in a St Petersburg cafe and arrested a Russian woman who was seen in a police video admitting planting the bomb that killed him and injured over 30 others.

Ukraine, which did not take responsibility for Sunday’s attack, blamed “domestic terrorism” for the murder of Mr Maxim Fomin, a Russian military blogger and cheerleader for Russia’s invasion of Ukraine who called himself Vladlen Tatarsky.

Darya Trepova, the 26-year-old Russian woman arrested for his murder, confessed in a video released by the Interior Ministry that she planted the bomb that killed him.

But unconfirmed Russian media reports said she told investigators she was set up and did not know she was carrying a bomb.

Mr Tatarsky’s murder appeared to be the second assassination on Russian soil of a figure closely connected to the conflict in Ukraine, after the car bomb killing of Ms Darya Dugina, daughter of a nationalist ideologue, outside Moscow last summer.

Russia also accused Ukraine at the time. Kyiv has denied involvement.

With over 500,000 followers on messaging service Telegram which is popular in Russia, Mr Tatarsky – who himself fought in Ukraine in the past – mixed ultra-nationalist messaging with criticism of the way Moscow is prosecuting what it calls its “special military operation” in Ukraine.

Mourners braved a snowstorm to lay flowers outside the St Petersburg cafe where he was killed, with many saying they were upset and angry.

Some Russian commentators said the bombing was the latest sign that violence related to the war in Ukraine is increasingly spilling into Russian territory.

Russia’s National Anti-terrorism Committee (NAC) said Ukraine’s intelligence services organised the bombing with help from supporters of jailed Kremlin critic Alexei Navalny.

That appeared to be a reference to the fact that Trepova once registered to take part in an anti-Kremlin tactical voting scheme that was promoted by Mr Navalny’s movement.

Mr Navalny’s allies, who have fled abroad since their movement was branded extremist by the Kremlin, rejected the accusation, saying it was more likely that Russia’s own intelligence services were behind the killing.

In the Interior Ministry video, Trepova confessed to giving Mr Tatarsky a small statue that was packed with the explosives that killed him but declined to say who gave her the statue.

“Can I tell you later?” she is heard saying.

Interior Ministry spokesman Irina Volk said Trepova was arrested in a rented flat in St Petersburg as part of an operation by the police and the FSB security service.

The Kremlin called Mr Tatarsky’s murder a “terrorist act”, citing the statement from the NAC as evidence that Ukraine might have been behind the killing.

“The active phase of the investigation is now under way,” said Kremlin spokesman Dmitry Peskov.

“We see quite vigorous steps to detain suspects. Let’s be patient and wait for the next announcements from our special services, which are working on this.”

Mr Mykhailo Podolyak, a Ukrainian presidential adviser, alleged on Sunday night that the killing was part of “an internal political fight” in Russia that he likened to spiders eating each other in a jar. He provided no evidence to back that assertion.

Unconfirmed Russian media reports said Trepova bought plane tickets to flee to Uzbekistan. Reuters could not immediately confirm that detail.

Trepova appeared on an Interior Ministry “wanted” list earlier on Monday. Court records showed she was detained on Feb 24, 2022, the day Russia launched a full-scale invasion of Ukraine, for taking part in what the authorities deemed an illegal anti-war protest.

The FSB said in March that it thwarted a Ukraine-backed car bomb attack on a prominent nationalist businessman who has been a cheerleader for Moscow’s war in Ukraine.

Ms Margarita Simonyan, editor-in-chief of state media outlet RT, welcomed Trepova’s arrest on Monday, saying her detention avoided what she called “a national disgrace”.

Ms Simonyan, like other hawkish commentators, made it clear on Telegram that she wanted Russia to hit back hard against whoever killed Mr Tatarsky.

“Well, well. Are we going to forget and forgive this?” she asked sarcastically. REUTERS