The deadly attack on a police bus in the French capital here has dramatically changed the course of the presidential poll campaign with the far-right candidate, Marine Le Pen, demanding the closure of all Islamist mosques, a media report said.

It was unclear whether the Thursday night attack would tip the balance of the vote in favour of Le Pen, who has vowed to take a tough line on "Islamic terrorism", media reported.

At a televised news conference on Friday, Le Pen called for the closure of all "Islamist" mosques in France, the expulsion of hate preachers and the reinstatement of French borders.

People on the French security services' watch list for radicalisation should also be expelled from France and have their French citizenship revoked, she said.

The three main candidates -- Centre-right candidate François Fillon, Le Pen and independent centrist Emmanuel Macron -- cancelled campaign events and instead made televised statements as under French election rules, Friday was due to be the final day of campaigning before Sunday's first round of voting.

In the televised statements they competed to talk tough on security and vowed a crackdown on Islamic State (IS) terror group that took responsibility for the Thursday night attack, media reported.

One police officer died after a gunman wielding a machine gun leapt out of a car and opened fire on the Champs-Elysees, Paris's most famous boulevard, as candidates were engaging in their final TV debate.

Prime Minister Bernard Cazeneuve, however, has accused Le Pen of trying to capitalise on the attack before the first round of polling on Sunday.

IS had swiftly claimed the attack was carried out by one of its "fighters".

The assailant -- Karim Cheurfi, a 39-year-old French national with a long and violent criminal record. He was shot dead as he tried to make his escape.

Prosecutors said a note defending IS fell out of his pocket, although there was no previous evidence of radicalisation.

He was also carrying the addresses of police stations.

French authorities, including the domestic security service, began a counterterrorism investigation into Cheurfi last month after learning of his increasing determination to establish communication with IS fighters in Syria and Iraq, a source close to the investigation told media on Friday.