The period of detention of three terror suspects arrested in France on Friday has been prolonged for 48 hours and they have been moved to the headquarters of anti-terror police near Paris, reports RFI.
They may have been planning to attack the Eiffel Tower, sources say.
The three - a 16-year-old girl, a man of 20 and a 33-year-old - were detained for a further 48 hours, sources said on Sunday.
Since the investigation is terror-related, they can be detained for up to six days.
On Saturday evening they were transferred from the south of France, where they were arrested, to the headquarters of France's anti-terrorist police at Levallois-Perret, just outside Paris.
A fourth man arrested on Friday was released after being cleared of all suspicion.