France has opened an anti-terror investigation after two journalists were stabbed in Paris today near the former offices of the Charlie Hebdo satirical magazine that was attacked by Islamist militants in 2015.

Prime Minister Jean Castex, who rushed to the scene, said the main attacker had been arrested and that the lives of neither of the wounded was in danger.

A second person was also in custody after the attack, in which witnesses said a meat cleaver or butcher's knife had been used as a weapon.

A local resident, who heard the attack, said there was a long, deathly shout from "a person who was screaming and screaming".

A neighbour said she saw blood on the ground and people pulling a wounded woman away into a building housing a news agency.

A police source said the main suspect was 18, known to security services, born in Pakistan and had been arrested with blood over him.

A second source said a meat cleaver had been found on the floor near a metro station.

French police officers stand at a security perimeter near the former Charlie Hebdo offices

The attack was carried out in what Mr Castex said was a "symbolic place" and coincided with the start this month of the trial of 14 alleged accomplices in the 2015 attack.

The court heard that the 14 had sought to avenge the Prophet Muhammad, nearly a decade after the weekly periodical published cartoons mocking him.

In 2015, gunmen killed 17 people in three days of violence that began when they opened fire at Charlie Hebdo's offices.

Al-Qaeda, the militant Islamist group that claimed responsibility for the 2015 attack, threatened to attack Charlie Hebdo again after it re-published the cartoons this month.

The national anti-terrorism prosecutor's office said it was investigating the case.

"The government is...determined with all its means to fight terrorism," Mr Castex said, adding that the two victims of today's attack had been taking a cigarette break.

Read more:
Charlie Hebdo republishes Muhammad cartoons for trial start

Police moved Charlie Hebdo's head of human resources from her home this week after threats against her life.

Today, TV footage showed ambulances, fire trucks and police cordoning off the area around Charlie Hebdo's former offices.

Paul Moreira, a journalist from Premieres Lignes media production company, told BFM TV that two of his colleagues had been wounded.

"It's somebody who was in the road with a meat cleaver who attacked them in front of our offices. It was chilling," he said.

France has experienced a wave of attacks by Islamist militants in recent years.

Bombings and shootings in November 2015 at the Bataclan theatre and other sites around Paris killed 130 people, and in July 2016 an Islamist militant drove a truck through a crowd celebrating Bastille Day in Nice, killing 86.