The French government is insisting it will keep a plan to hold the 2024 Paris Olympics opening ceremony on the River Seine even after a deadly attack in the French capital at the weekend amplified existing security concerns.

Sports Minister Amelie Oudea-Castera told French radio that the plan could still be adapted within the idea of the river flotilla, as media reports indicated grave concern within the security forces that the ceremony could be vulnerable to attack.

A man known to the authorities as a radical Islamist with mental troubles on Saturday fatally stabbed a German tourist close to the Eiffel Tower by the River Seine in what prosecutors are investigating as a suspected act of terror.