French counter-terrorism investigators are investigating a dual Russian-Ukrainian citizen who was seriously injured when a homemade explosive device detonated in a hotel on the outskirts of Paris.
Emergency services treated the 26-year-old with severe burns on Monday evening, counter-terrorism authorities said on Wednesday.
Investigators found materials used in bomb-making at the scene, where one of the explosive devices detonated. The man was taken into custody.
Authorities opened an investigation into the man for participating in a criminal terrorist organization, planning to carry out criminal offences and possession of explosive devices.
The investigation has been taken over by the France's General Directorate for Internal Security.
The Le Journal du Dimanche newspaper reported that the man is believed to be a Russian spy targeting French military equipment for Ukraine.
Investigators reportedly discovered ammonium nitrate, a cheap explosive favoured by terrorists, in the man's hotel room in Roissy.
According to the Le Parisien newspaper, the injured man is said to have told police that he had wanted to make mobile phone batteries when the explosion occurred.
In the run-up to this summer's Olympic Games, France has reported a number of cases of possible Russian influence and attempts at destabilization.
In May, the Holocaust memorial in Paris was defaced with paint, while five coffins covered with French flags bearing the inscription "French soldiers killed in Ukraine" were discovered under the Eiffel Tower on Saturday.