A Romanian man has been detained on suspicion that he was linked to a group involved in the November 2015 Paris attacks.
Organised crime prosecutors questioned the man, identified only as "Ibrahim", in the central Romanian city of Pitesti.
According to a statement, the suspect used to live in an unidentified European Union state where he adopted a radical form of Islam.
It said he was connected to people who claimed responsibility for the attack on the Bataclan concert hall in Paris.
The statement said the 39-year-old visited a Romanian military base in 2015, sending information to a jihadi group in an EU country.
He said he wanted to take part in an attack on the base.
Chief organised crime prosecutor Daniel Horodniceanu said authorities had not acted earlier "for tactical reasons".
The man risks up to 20 years in prison.