France's President Emmanuel Macron is seeking to extend a state of emergency, in place since Islamic State attacks on France in 2015, following the bombing at a concert in Manchester.
Mr Macron said in a statement he will ask parliament to prolong the measure from July 15, its current expiration date, until November 1.
It would be the sixth extension of the state of emergency, which gives police exceptional powers.
He made the decision after a security meeting on Wednesday in which top officials "studied the implications of this new terrorist attack on measures of protection to ensure the security of our compatriots".
Mr Macron also asked his government to prepare draft legislation to reinforce security measures permanently beyond the state of emergency.