Russia's Federal Security Service (FSB) on Monday accused Ukraine's secret service of carrying out the weekend murder of Darya Dugina, the daughter of an ultra-nationalist Russian ideologue, Russian news agencies reported.

Dugina, the daughter of prominent ideologue Alexander Dugin, was killed on Saturday evening when a suspected explosive device blew up the Toyota Land Cruiser she was driving, Russian investigators said. Ukraine has denied involvement.

The FSB said the attack was carried out by a Ukrainian woman born in 1979 whom it named.

It said the woman and her teenage daughter had arrived in Russia in July and spent a month preparing for the attack by renting an apartment in the same housing block and researching Dugina's lifestyle, according to an FSB statement carried by Russian news agencies.

The assailant had attended an event outside Moscow on Saturday evening which Dugina and her father were also at, before carrying out a "controlled explosion" of Dugina's car, and fleeing Russia to Estonia, the FSB was quoted as saying.

Reuters was unable to confirm the reports.

Ukraine is not a "criminal state" like Russia and so had nothing to do with the weekend killing of Dugina, according to a top Ukrainian official.

"I want to emphasize that Ukraine had nothing to do with this," Mykhailo Podolyak, Ukraine's senior presidential adviser, told local channel ICTV on Sunday.

"They don't understand that we're not a criminal state like Russia," he also said, adding that blaming Ukraine for the incident is probably meant to justify the drafting of more soldiers for

Russia's war against its western neighbor is now in its sixth month.

In recent years Moscow has been accused of being behind the assassinations of Russian critics and defectors abroad, including the near-deadly poisoning of ex-spy Sergei Skripal and his daughter in 2018 in Salisbury, England.

On Saturday's incident, Russian Foreign Ministry spokesperson Maria Zakharova pointed to what she called Ukraine's "policy of state terrorism."

Reports claim that Dugina's father, called "Putin's brain," was the intended target.

Russia's Investigation Committee said that the bombing "was planned in advance and committed on order" and that authorities are investigating.

Born in 1992, Dugina, like her father, was involved in journalism, philosophy and political science.