A French judge in France has opened criminal proceedings against four men suspected of links with terrorist networks in west Africa.
The four were detained in the Paris area on Tuesday. Three are reported to be French and one is from Mali.
The BBC reports two of the four are in preventive detention and the other two have been released.
French officials have said they were arrested in connection with the case of a French national arrested in Niger while trying to join Jihadist groups in Mali last year.
The man was extradited to France, where criminal proceedings were launched against him in August.
France increased its domestic terror threat level after French forces entered Mali on 11 January against insurgents in Timbuktu and other parts of northern Mali.