Paris - French President Francois Hollande said Tuesday's attacks in Brussels that killed at about 35 people struck at "the whole of Europe".
"Through the attacks in Brussels, the whole of Europe has been hit," Hollande said in a statement, urging the continent to take "vital steps in the face of the seriousness of the threat".
French Prime Minister Manuel Valls said: "We are at war. Over the past few months in Europe, we have endured several acts of war."
The prime minister said later it was "time to adopt" a Europe-wide system of tracking airline passenger names despite misgivings about the use and security of personal data, notably among left-wing MEPs.
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"I say in particular to the socialist and environmental groups in the European Parliament: everyone should assume their responsibilities," Valls told French parliament. "We have lost enough time on this issue."
France has led the calls for adopting the Passenger Name Record (PNR) system first mooted in 2010, which will cover all international and internal EU flights while providing safeguards on access to and use of the data collected.
The European Parliament's Civil Liberties Committee voted to approve the deal in December, less than a month after the Paris attacks, and the body was meant to take up the measure early this year.
The November 13 attacks in Paris claimed 130 lives, 10 months after attacks on the satirical newspaper Charlie Hebdo and a Jewish supermarket left 17 dead.
Several of the jihadists involved came from Brussels.
The last surviving jihadist of a 10-man team who carried out the November attacks, Salah Abdeslam, was arrested in Belgium on Friday, where the attackers had rear bases and what appears to be an extensive network of support.
Speaking on Sunday, Belgian Foreign Minister Didier Reynders said Abdeslam told investigators "he was ready to restart something in Brussels".
Following Tuesday's bloodshed in Brussels, Hollande spoke with Belgium's Prime Minister Charles Michel, and the two exchanged "information, intelligence" and discussed "questions of police and security cooperation," his office said.
French Interior Minister Bernard Cazeneuve earlier announced that Paris was deploying 1,600 additional police to border crossings and air, sea and rail infrastructure after the Brussels attacks.
Germany and the Netherlands also announced stepped up security measures at borders, airports and rail stations.