French prosecutors have placed a Russian artist and his girlfriend under investigation over the leaking of a sex video that brought down a close ally of Emmanuel Macron.

Pyotr Pavlensky and Alexandra de Taddeo are facing charges of invasion of privacy and publishing images of a sexual nature without consent over the leaking of the video that forced Benjamin Griveaux to end his campaign to become mayor of Paris.

Pavlensky is also being investigated over a knife fight at a New Year’s Eve party in Paris. Prosecutors requested on Tuesday that he be placed in detention over that incident.

Pavlensky, 35, and De Taddeo, 29, were taken into custody on Saturday and questioned for two days. They will be taken before an investigating magistrate later on Tuesday to face possible charges.

Q&A Who is Pyotr Pavlensky? Show The 36-year-old Russian conceptual artist fled to France in 2017 after being detained and questioned over sexual assault allegations made by a female actor. He denies the allegations, claiming they were politically motivated.

A St Petersburg native and art school graduate, he gained fame after the 2012 trial of the punk protest group Pussy Riot, which he said convinced him of the need for a radical turn in art. He encased himself naked in barbed wire and cut off his earlobe while perched on top of a psychiatric hospital. When he was arrested for setting fire to the doors of the headquarters of the FSB security service, he incorporated his arrest and trial into his art. In 2012 he sewed his mouth shut to protest against censorship and a year later he nailed his scrotum to the cobblestones of Red Square. In his adopted country, he set fire to a Bank of France office and has supported the gilets jaunes protest movement. But the release of a sexual video of a Paris mayoral candidate may be his most explosive stunt to date. In a 2014 interview, he bragged of not fleeing punishment for his art: “Whenever I do a performance like this, I never leave the place. It’s important for me that I stay there." Yet Pavlensky did leave Russia after the sexual assault allegations. Andrew Roth

Pavlensky, an artist and activist who fled Russia in 2017, has admitted publishing the video showing a man masturbating, along with a series of text messages.

De Taddeo is believed to have been the recipient of the video and messages, which were uploaded on to a website created by Pavlensky and widely shared on social media.

Griveaux, 42, a former government spokesman, pulled out of the running for Paris mayor after the scandal broke.

The leaking of the video triggered an outpouring of sympathy for the politician in France, where politicians and the media have dismissed sex scandals as private affairs.

Pavlensky, who made global headlines in 2013 when he nailed his scrotum to Red Square in Moscow as a form of political protest, said last week he had wanted to expose the “hypocrisy” of the married father of three, who had made families a core theme of his campaign.

With just a month to go until the municipal elections, the former health minister Agnès Buzyn was scrambling to take his place as the Paris mayoral candidate of Macron’s La République En Marche party.

She faces a difficult challenge to oust the Socialist incumbent Anne Hidalgo; Griveaux was already running in a distant third place before the video emerged.

Pavlensky, who has a long record of radical protests, was given asylum in France in 2017 after falling foul of Russian authorities.

He was originally detained on Saturday after being accused of pulling a knife during a brawl at a New Year’s Eve party in Paris. Investigators later shifted their focus to the leaked sex video.