France says it has received fresh warnings from the Saudi authorities of an imminent terrorist attack.
Interior minister Brice Hortefeux says the threat reportedly came from Al Qaeda in the Arabian Peninsular.
In a radio and television interview on Sunday, Mr Hortefeux said the group was targeting the European continent and in particular France.
The threat is real and we remain alert, he said.
Mr Hortefeux said there was a warning from Interpol on 9 September and then a second warning a week later of a possible attack by a female suicide bomber.
Western security officials have also warned that al-Qaeda may be planning attacks in Europe similar in Mumbai in 2008 when 166 people were killed.
France's security threat level remains one level below the highest level of scarlet.