Terrorist violence looms large as France goes to polls on Sunday

France goes to the polls on Sunday with terrorist violence casting a shadow over its Presidential election, after the shooting of a policeman on the Champs Élysees.

The attack, claimed by the Islamic State, threw open radically opposing visions and discussions among the Presidential candidates.

Frontrunner Emmanuel Macron accused his two closest rivals of using the killing of Xavier Jugele, the policeman who died, and the serious wounding of two other police officers to score political points ahead of Sunday's first-round vote, The Guardian reports.

Macron said far-right Front National leader Marine Le Pen with who he is neck-and-neck in polling for the first-round vote and rightwing candidate François Fillon were engaging in one-upmanship in their response to the attack.

Independent Centrist Macron said it was vital for people to summon a "spirit of responsibility in what is an extreme period" and come up with a measured response to "a tragic event that has left our country in grief".

"We must not give way to panic, nor in any way allow any attempt to manipulate these events," he said at a press conference. "The terrorists want to destabilise the country . at a time when the French are deciding on their future."

He promised that if elected he would create a Presidential unit to "work around the clock" to tackle the ISIS. "A vigorous offensive will be taken to fight Islamic radicalisation, especially on the internet," he said. "This is a moral challenge, a challenge for civilisation."

He accused Le Pen of lying when she claimed she could have prevented previous attacks, had she been in office. "She won't be able to protect our citizens," Macron said.

Le Pen too had earlier taken a characteristically tough stance against Islamic extremism, branding it a "barbaric and monstrous totalitarian ideology" and insisting France immediately take back control of its borders from the European Union.

She said France must engage in a "war against terrorism" and accused successive French governments of being too lax towards fundamentalists. She demanded the immediate expulsion of foreigners linked to Islamism and flagged as suspects considered a potential risk to national security.

"The Islamist, Salafist ideology has no right to be in France and should be banned. Preachers of hate should be expelled and their mosques closed," she had said.

Like Le Pen and Macron, Fillon, the rightwing candidate whose campaign has been hit by allegations he paid his wife, Penelope, public money for parliamentary assistance she did not provide, cancelled planned end-of-campaign meetings on Friday.

He said France must show it was united, and not afraid. For years "I have been warning that we are confronting an Islamic totalitarianism, in other words, an ideology that is radical, organised and expansionist," he said.

Cazeneuve criticised Le Pen and Fillon's reactions, claiming they were excessive and divisive.

Polls have suggested Le Pen and Macron are the most likely candidates to go through to the second-round runoff, but Fillon and the hard-left candidate Jean-Luc Melenchon are only two or three points behind.

Campaigning for the first round ends at midnight on Friday and polls suggest any two of four leading candidates could go through to the runoff on May 7.

French Prime Minister Bernard Cazeneuve said the government had reviewed its extensive election security measures and was fully mobilised in the wake of the attack.

Cazeneuve said more than 50,000 police and gendarmes and 7,000 soldiers would be on duty for Sunday's first-round vote in the two-stage election, and nothing could be allowed to "hamper this democratic moment".