The two candidates for the French presidency, Emmanuel Macron and Marine Le Pen, are attending a ceremony in Paris in honour of the policeman shot dead on the Champs Elysées last week.
It is the first time the top two candidates in Sunday’s first round of voting have appeared together publicly.
Xavier Jugelé, 37, was killed by convicted criminal Karim Cheurfi.
Current President François Hollande called for unity in the “long and difficult fight against terrorism”.
“Once again France has lost one of its bravest sons. Once again the Republic has lost one of its most valuable guardians,” he said.
The issue of security sharply divides the presidential candidates.
Ms le Pen wants France to reintroduce border controls and deport all foreigners on a terror watchlist.
Mr Macron, an advocate of open borders, has urged French citizens not to give in to fear.
Mr Jugelé, 37, was an active campaigner for gay rights, say French media.
Originally from the Loire Valley region in central France, he had reportedly been serving in the capital since 2014.
On 13 November 2015, he was deployed to secure the area around the Bataclan concert hall after the attack by the so-called Islamic State group.
When the venue reopened last November with a concert by Sting, Mr Jugelé was there again, telling the US magazine People: “I’m happy to be here… We’re here tonight as witnesses. Here to defend our civic values. This concert’s to celebrate life. To say no to terrorists.”