Huge swathes of riot police in Paris had to deploy tear gas after being pelted with flares and other makeshift weapons in a pre-election riot.

The planned march, just a day before the country goes to the polls in the first round of the leadership vote, turned ugly with citizens and police clashing, in violent scenes.

Masked protesters hurled bottles and stones at legions of officers who flooded central Paris after a colleague was gunned down in ISIS inspired assassination on the Champs Elysee.

The 200-strong mob hijacked a peaceful rally organised by left-wing unions and communists.

Huge swathes of riot police in Paris had to deploy tear gas after being pelted with flares and other makeshift weapons in a pre-election riot

The planned march, just a day before the country goes to the polls in the first round of the leadership vote, turned ugly with citizens and police clashing, in violent scenes

Masked protesters hurled bottles and stones at legions of officers who flooded central Paris after a colleague was gunned down in ISIS inspired assassination on the Champs Elysee

Marching bands and flag waving activists had gathered at the famous Place de la Republique before settling off along the capital's streets.

But black-clad anarchists infiltrated the demonstration, launching their terrifying assault on the forces of law and order at the Place de la Bastille - the birth place of the French Revolution.

It comes after Marine Le Pen's campaign co-ordinator claimed that France could break into civil war, if the nation continues to be hit with terror attacks.

Thursday's murder of police officer Xavier Jugele by ISIS fanatic Karim Cheurfi is the latest in a long list of Islamist attacks in France.

Marching bands and flag waving activists had gathered at the famous Place de la Republique before settling off along the capital's streets

But black-clad anarchists infiltrated the demonstration, launching their terrifying assault on the forces of law and order

Riot police stood on the corner of a street after some of the order had begun to be restored

And Jean Messiha told BBC Newsnight that a continuation of 'feeble' leadership will result in ISIS strengthening their grip within the country, allowing them to carry out even more attacks on a larger scale.

He added that if that happens, there will be mutiny within the country, with France already having been in a state of emergency since 2015 due to a spate of terror attack that have killed more than 230 people in the past two years.

Mr Messiha said: 'She [Le Pen] is the only one who can heal the division in this country because she is the only one to call for authority back in the streets of Paris and the state must use its authority to restore state power in the streets.'

'If the state is feeble, you will have massive terrorist attacks – more and more in quantity and deaths, and this time, there will be civil war.'

Policemen take a minute of silence for their colleague killed on a terrorist attack on the Champs-Elysees

The crowd gathers in a circle around some flowers as the wellwishers pay their respects

A woman kisses a police officer after giving him flowers, during a demonstration in what was described as a march of support for all French security forces

The first poll conducted entirely after Thursday's attack suggested Le Pen had gained some ground on Macron.

While he was still seen winning the first round with 24.5 percent, his score slipped half a percentage point while Le Pen's rose by one to 23 percent.

Conservative Francois Fillon, a former prime minister, and the far left's Jean-Luc Melenchon were both down half a percentage point on 19 percent in the Odoxa poll for the newspaper Le Point.

The leading candidates have clashed over how to keep citizens safe in the wake of the attack, as residents in overseas territories were pictured casting their votes.

Cheurfi, 39, drove his silver Audi on to the Champs Elysee, the most famous street in the French capital, and 'targeted' officers using a Kalashnikov on Thursday night.

He killed 37-year-old policeman Xavier Jugele as he sat in a patrol van at a red light and hit another police officer in the chest, but he survived because he was wearing a bulletproof vest.

Marine Le Pen at a press conference in Paris. Experts believe that her poll ratings could be boosted by Thursday's terror attack

Jean Messiha told BBC Newsnight that a continuation of 'feeble' leadership will result in ISIS strengthening their grip within the country, allowing them to carry out even more attacks on a larger scale

Cheurfi then tried to run away with his rifle and wounded a third officer before being gunned down near a Marks & Spencer store on the world-famous avenue.

And experts agree the atrocity could tip the scales in Le Pen's favour, ahead of Sunday's election.

Fredrik Erixon, director at the European Centre for International Political Economy, told CNBC: '[It could lead to] a greater performance of Marine Le Pen than otherwise would have been the case.

'It's difficult to see how this attack will not play into the hands of political forces that want this campaign to be focused only on issues around migration and terrorism.'

Vishnu Varathan, senior economist at Mizuho Bank, added: 'The Paris gunman attack may well swing support in her favor; and this may not be picked up by the polls in a timely manner.'

More than half of police officers in France had already said they were voting for Le Pen because of her strong anti-terror stance, according to an IFOP poll.

A woman casts her ballot at a polling station on the French overseas archipelago of Saint-Pierre et Miquelon

A municipal employee prepares ballot boxes on the eve of the first round of the French presidential election at a polling station in Tulle

A woman casts her ballot at a polling station on April 22, 2017 in Remire Montjoly, French Guiana

Le Pen yesterday called for foreign terror suspects to be kicked out the country despite the fact the ISIS gunman was French

Karim Cheurfi, 39, drove his silver Audi on to the Champs Elysee, the most famous street in the French capital, and 'targeted' officers using a Kalashnikov on Thursday night

Mourners gather to leave flowers and notes for policeman Xavier Jugele who was shot dead

MAIN CONTENDERS IN FRENCH PRESIDENTIAL ELECTION Emmanuel Macron A former economy minister of Francois Hollande, the 39-year-old Centrist is the front-runner in the polls. He started a political movement called 'En Marche' that he presents as neither right-wing nor left-wing. The pro-European former investment banker is expected to become France's youngest-ever president because polls suggest if he reaches the run-off on May 7 he would defeat far-right candidate Marine Le Pen. Three surveys show Macron having a slight edge over Le Pen with 23-25 per cent against 22-23 per cent. Macron is married to his former French teacher Brigitte Trogneux, 20 years his senior, and has seven step-grandchildren. Marine Le Pen Le Pen is the candidate of her far-right National Front party. Bolstered by Donald Trump's victory as well as the Brexit result, she is campaigning on an anti-immigration, anti-Islam, nationalist plaform. Following the Champs-Elyees shooting she called for foreign terror suspects to be expelled immediately and said it was a 'ceaseless and merciless war' against France which required 'a presidency which acts and protects us'. She has also pledged to beef up law and order in her manifesto, with 15,000 more police officers, deporting foreign criminals and closing extremist mosques. A study released earlier this week revealed that 51 per cent of French police officers plan to vote for Le Pen in the upcoming polls. That is more than double the number of people who are backing Macron (16.5 per cent). According to the polls, she is currently on 22/23 per cent, but she is likely to be defeated in the second round by Macron. Francois Fillon The longtime No. 2 of former president Nicolas Sarkozy, Francois Fillon was initially installed as the favourite. However his campaign has been dogged by allegations that his Welsh wife and two oldest children improperly received public funds. He said he would step aside before performing a U-turn and he has since received a last-minute boost in the polls and is currently on 20 per cent. Fillon, who penned a pre-election book called 'Beating Islamic Totalitarianism', declared that 'the fight against terrorism must be the absolute priority of the next president'. Vowing to 'destroy Islamic State', he added: 'We are at war, there is no alternative, it's us or them.' Jean-Luc Mélenchon Far-left firebrand Mélenchon the 65-year-old is running for president for the second consecutive time after finishing in fourth place five years ago with 11 per cent of the vote. This year, Melenchon's debating skills, anti-capitalist rhetoric, pugnacity and grasp of social issues have seen him surge in the campaign's closing stages, with 19 per cent in the polls. Melenchon promises to tax the rich and spend heavily, to renegotiate France's role in the 28-nation EU and international trade pacts. He also wants to get rid of what he calls the 'presidential monarchy' by giving more power to parliament, and to stop France's use of nuclear power, the source of nearly 80 per cent of the country's electricity. If Melenchon makes it to the runoff, he is projected to beat both Le Pen and Fillon by comfortable margins although he is seen losing to Macron 41 per cent to 59 per cent. Benoît Hamon Hamon is polling in a distant fifth place ahead of Sunday's first-round election and has little chance of reaching the decisive May 7 run-off - a failure that could crush his Socialist party. He wants to legalise cannabis and tax the wealth generated by robots that take the jobs of humans. Advertisement

But the latest attack in the heart of Paris could send voters flocking to Le Pen, who has pledged to beef up law and order in her manifesto, with 15,000 more police officers, deporting foreign criminals and closing extremist mosques.

US President Donald Trump said today it would 'have a big effect on presidential election' as the French people 'will not take much more of this'.

Macron appealed to voters to keep a cool head in the wake of the attack.

He said: 'What our attackers want is death, symbolism, to sow panic (and) to disturb a democratic process, which is the presidential election.'

US President Donald Trump said today it would 'have a big effect on presidential election' as the French people 'will not take much more of this'

French police officers and forensic teams searched a vehicle which was close to the scene on the Champs-Elysees in Paris

The attacker emerged from a car and used an automatic weapon to shoot at officers at the centre of the Champs-Elysees

He tore into Le Pen, accusing her of lying with claims that previous attacks wouldn't have happened under her watch.

'She won't be able to protect our citizens,' Macron said of Le Pen.

He added: 'There's no such thing as zero risk. Anyone who pretends (otherwise) is both irresponsible and deceitful.'

France's Thatcherite candidate Francois Fillon has said 'we are at war...it's us or them' in the wake of the Champs-Elysees terror attack as voters are expected to flock to National Front leader Marine Le Pen in Sunday's presidential election.

Fillon, who penned a pre-election book called 'Beating Islamic Totalitarianism', declared that 'the fight against terrorism must be the absolute priority of the next president'.

Vowing to 'destroy Islamic State', he added: 'We are at war, there is no alternative, it's us or them.'

Socialist Benoit Hamon tweeted his 'full support' to police against terrorism.

French Prime Minister Bernard Cazeneuve, a Socialist, said Le Pen's National Front 'after each attack, seeks to exploit it and use it for purely political means.'