Two men were arrested on Friday at Montparnasse train station in Paris after one threatened to blow himself up, even though he did not have the means to do so, the prosecutor's office said.
The two homeless men were charged in connection with an "apology" for a terrorist act, the office said. It did not elaborate.
One of the men, a French national, had been drinking and possibly has mental health issues. He shouted that he was going to blow himself up, the office said.
The two men had nine small camping gas bottles in their luggage, but no way of making them explode, the office said.
The second suspect, believed to be a Libyan national, had been under investigation for breaking immigration laws, the office said.
(Reporting by Mathieu Rosemain, writing by Geert De Clercq, editing by Nick Macfie)
