French President Francois Hollande is calling for new security measures around the country's presidential race, notably to protect against hacking.
Mr Hollande's order came after the campaign of centrist Emmanuel Macron accused Russia of trying to sway the April 23-May 7 election.
President Hollande asked top security officials to present electoral security measures next week "including in the cyber domain".
Mounir Mahjoubi, head of digital campaigning for Mr Macron, said that his team identified thousands of hacking attempts originating from Ukraine in recent weeks.
Mr Mahjoubi says the attempts coincided with what he called a fake news operation targeting Mr Macron in Russia-sponsored media in France.
Mr Macron's leading rivals, Francois Fillon and Marine Le Pen, want to lift sanctions against Russia, while Mr Macron has been less friendly toward Moscow.