On Monday, several activists stole a 40,000-euro statue of Macron from the Grevin Museum and placed it in front of the Russian embassy and later outside the headquarters of French electricity giant EDF to protest France's economic ties with Russia.

The statue, estimated to be worth 40,000 euros ($45,500), was returned to police on Tuesday night but two activists, a man and a woman, were detained on Monday, their lawyer Marie Dose said.

Jean-François Julliard, head of Greenpeace France, said that the detained pair were people who drove a truck during the protest in front of the Russian embassy, and not those who "borrowed" the statue from the museum.

"They have spent three nights in a cell," said Dose, denouncing the detention as "completely disproportionate".

The lawyer denounced the "deplorable" conditions in which the two activists were being held, "attached to benches for hours and dragged from police station to police station".

One activist spent the night without a blanket and was unable to lie down because her cell was too small, the lawyer said.

"The other had to sleep on the floor because there were too many people in the cell," she added.

"This treatment is worrying for Greenpeace activists and raises the question of a dangerous shift in the criminal response to acts of civil disobedience," she said.

The pair will appear before an investigating magistrate on Thursday as part of a judicial inquiry into the "theft of a cultural object on display", the Paris prosecutor's office told AFP.

The judge will decide whether to charge them.

The lawyer argued that "no harm resulted from the non-violent action", arguing that "all offences" ceased to exist once the statue has been returned to the museum.

The Grevin Museum filed a complaint on Monday but subsequently took the matter in good humour. "The figures can only be viewed on site," it said on its Instagram feed.

The activists managed to slip out through an emergency exit of the museum by posing as maintenance workers.

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