An Islamic State "soldier" who stabbed a man to death and injured four others in an attack in Paris was on an anti-terror watchlist of suspected extremists, it has emerged.

Police in the French capital have launched a terror investigation following the attack on Saturday night, which was carried out by a 21-year-old man who was born in the Russian republic of Chechnya, where Islamic extremism has long simmered.

The suspect, believed to be a French citizen, was on the so-called "S file" of people suspected of radicalised views who could pose a threat to national security, sources said.

He had no record of arrests or criminal activity, and did not know his victims, interior ministry officials said.

His mother and father are being held in custody for questioning.


Image: A bullet hole at the site of the attack

The news agency Reuters has seen a photo claiming to show the attacker, who is bare-chested, bearded, and wearing black trousers.

It has not been confirmed if the image shows him from the time of the attack, which took place just before 9pm in Rue Monsigny, where Paris' Opera and landmark shops are located.

He shouted "Allahu Akbar" - God is great in Arabic - according to witnesses, the Paris prosecutor Francois Molins said.

A police source said he also shouted: "Kill me or I kill you."

Police union representative Rocco Contento said officers shot the man as he ran at them shouting: "I will kill you, I will kill you."

Image: Emergency services respond as one person is killed and four are injured

In a conflicting account, the French news channel BFMTV reported that officers shot him while he was on the ground suffering from cardiac arrest.

The IS news agency Amaq claimed the suspect was one of its "soldiers" who carried out the attack in response to the terror group's calls for supporters to target members of the US-led military coalition fighting the extremists in Iraq and Syria.

France's military has been active in the coalition since 2014.

Image: One person was stabbed to death and the knifeman was shot dead by police

French President Emmanuel Macron said "France once again paid the price of blood but did not give an inch to the enemies of freedom".

He praised "the courage of the policemen who have neutralised the terrorist."

Image: The attack happened on Rue Monsigny in the second arrondissement. Pic: Google Maps

The person who was fatally stabbed is believed to be a 29-year-old man, while those who were injured are thought to be out of danger. They include a 34-year-old man from Luxembourg.

Video on social media showed people fleeing the area, which was near St Augustine Street and is lined with restaurants.

A witness who was sitting in a Japanese restaurant with his girlfriend told Le Parisien: "Just before 9pm, we saw people rushing inside the restaurant screaming that a man was outside with a bloody knife.

Image: Policemen stand guard in Paris centre after one person was killed and several injured in a knife attack

"People were throwing themselves on the floor in panic.

"Five minutes later there was a second scare and customers blocked the door of the restaurant for fear the attacker had slipped inside.

"Then it calmed down. Outside, even the police seemed a bit lost at first."

Milan, 19, said he saw "several people in distress" including a woman with wounds to her neck and leg.

"Firemen were giving her first aid. I heard two, three shots and a policeman told me that the man had been overpowered," he said.

Image: The knifeman allegedly shouted 'Allahu Akbar' as he carried out the attack

French interior minister Gerard Collomb praised "the cool composure and responsiveness of the police forces that have neutralised the assailant", while Anne Hidalgo, the mayor of Paris, said the city had been "bruised".

France is on high alert after a string of jihadist attacks has claimed the lives of more than 245 people, including 90 at the Bataclan concert hall in November 2015.