French police on Wednesday arrested a 26-year-old Russian-Ukrainian who was seriously injured when explosives in his possession detonated, in a hotel room in the north of Paris, a source close to the PNAT counter-terrorism prosecutor’s office said.

The man “suffered serious burns after an explosion” on Monday, this source said.

From the search that followed, materials for the manufacture of explosive devices were found in the room.

The source said PNAT, which works with France’s domestic intelligence agency, is conducting a preliminary investigation into the man, who is suspected of involvement in a terrorist plot.

Not even the embassy of Ukraine, nor did the Russian embassy in Paris respond to a request for comment.

CDG airport, which is near the hotel where the 26-year-old was arrested, said its operations were not affected.

France has been put on high alert with less than two months to go until the Paris Olympics. Last month, security services said they had thwarted the first attempted attack on the Games, with the arrest of an 18-year-old Chechen man who was plotting a suicide attack on the St-Etienne stadium.