British Prime Minister Theresa May says the UK and France will work together to press internet companies to reduce extremist material online.
May is meeting French President Emmanuel Macron on Tuesday in her first foreign trip since a catastrophic election that weakened her leadership as Britain heads into tough talks on quitting the EU.
With Macron by her side, May said the two nations will do more to "stamp out this evil" of terrorism.
Major internet companies have failed to live up to prior commitments to do more to prevent extremists from finding a "safe space" online she said, and they will look at creating legal liability for internet companies if they fail to do so.
France and Britain have experienced several extremist attacks in the past few years.
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Meanwhile, her French counterpart focused on the looming start date for Brexit talks.
The door is still open for the UK to remain in the European Union, Macron said, but stressed "the decision has been taken by the sovereign British people. I do respect that".
Macron said he wants Brexit negotiations to start as soon as possible, following a working dinner with May.
British officials have suggested they won't be able to formally start Brexit negotiations next week as planned.
Macron said he wants the negotiations to be led and coordinated by a European mission.
The two are on opposite fronts of the Brexit negotiations - Macron wants the remaining EU nations to stand tough and unite even more closely as Britain leaves.
The two leaders are to watch a France-England football match that will honour victims of the attacks with a moment of silence and the Oasis song Don't Look Back in Anger played by the French Republican Guard.
