President Volodymir Zelensky’s aide Mykhailo Podolyak insisted Kyiv had “nothing to do” with the murder of Darya Dugin.
Political campaigner Darya was killed instantly when the device exploded as she drove her father Alexander Dugin’s Toyota Land Cruiser.
Bearded Dugin – dubbed “Putin’s Brain” or “Putin’s Rasputin” for his influence as an adviser to the Kremlin Tyrant – was due to travel with her but changed his plans.
Dugin’s associate Andrei Krasnov said they had been at a conference together and 29-year-old Darya was probably the victim of an attack meant for her father.
Russian foreign ministry spokeswoman Maria Zakharova warned that if the evidence pointed towards Kyiv it would amount to “state terrorism”.
But Mr Podolyak said: “I confirm that Ukraine, of course, had nothing to do with this.
“We are not a criminal state, like the Russian Federation, and moreover we are not a terrorist state.”
He blamed “political factions” in Russia and dubbed the incident “Karmic” payback for Dugin’s vociferous support for Putin.
Dugin, a far-right philosopher who claims Ukraine should be absorbed within Russia, had been giving a lecture at Saturday’s Tradition festival.
He and Darya were due to leave the event at Bolshiye Vyazemy, on the capital’s outskirts, together, before he changed his plans at the last minute.
Footage circulated on social media appeared to show the 60-year-old examining the car’s burning wreckage in shock.
Television news showed investigators collecting fragments of debris from the scene of the accident.
The Russia Federation’s Investigative Committee ordered its central branch to conduct a murder inquiry with “all versions” of events examined.
A statement said: ”An explosive device was placed on the underside of the car on the driver’s side.
“Darya Dugina, who was behind the wheel, died at the scene. The investigation believes that the crime was planned in advance and was of a contractual nature.”
Experts say her father believes Russia should be more aggressive towards its neighbours and was the inspiration behind last February’s invasion of Ukraine.
Darya shared his ultra-nationalist beliefs and, like him, was sanctioned by Britain and America for spreading disinformation about the war.
In May, the website editor described the conflict as a “clash of civilisations” and gloated about being targeted by the Western boycott.