Prosecuters in France have launched an investigation into claims that police have been firing 'defensive bullets' at protesters after footage emerged of a flash ball hitting onlookers on a balcony.

The footage, which emerged on social media on January 11, showed a flash ball hit a a balcony where five people had been watching anti-government protesters in the eastern city of Lyon.

The student who filmed the scene and identified solely as Marie told the Parisien news outlet that they were hit by a grenade or an defensive bullet which exploded near their window.

An investigation is underway after a suspected flash ball was seen hitting a window where five people had been watching anti-government protesters in Lyon, France

The student, who had been stood on a balcony, watched the anti-government protesters in the eastern city of Lyon

The onlooker said: 'We were filming the demonstration and were hit by a grenade or an LBD [defensive bullet], I don't know which, and it exploded at our window on the fourth floor!

'The thing bounced off my friend's arm from the window and ended up running through the apartment. He was lucky he had a big sweater on, which absorbed the shock.'

Maire added: 'Then we panicked, and we went out into the lobby because our eyes were burning.'

At least 15 people have suffered serious eye injuries during months of street protests in France against measures including President Emmanuel Macron's pension reforms.

Among those who have actually lost an eye are Jerome Rodrigues, one of the leaders of the Yellow Vest movement, which is named after the fluorescent road jackets members wear

As the Lyon authorities opened an enquiry, another video shot in Paris last week showed police officers using batons to push protesters back.

As the protesters flood onto the streets on January 11, a flash ball suddenly hits the balcony. The filmer, who identified solely as Marie told the Parisien news outlet that they were hit by a grenade or an defensive bullet which exploded near their window

The filmer said the flash ball bounced off their friend's arm from the window and ended up running through the apartment

A spokesman for Paris prosecutors confirmed that an investigation had been opened into 'violence committed by a person holding public office.'

In turn, a Paris police spokesman said such videos - which have appeared online and gone viral - were often viewed 'out of context'.

'Police and gendarmes were attacked by violent people and retaliated with tear gas and defensive bullet launchers,' he said.

The defensive bullet launchers are known as LBDs in France, and fire 40-millimetre rubber balls.

Hundreds of police tear gas cannisters are also used during all violent demonstrations, and often cause severe injuries too.

In another video shared on social media police in armour were seen using batons to push protesters back

Protesters lay on the ground as the police pushed them back and the violence continued

During riots across the country on Saturday, President Macron's prime minister Edouard Philippe announced a U-turn on a move to raise the full-benefit retirement age to 64 from the present 62.

With a crippling transport strike also already in its sixth week, the new age limit was withdrawn.

But the concession will not end either the strike or the demonstrations.

Militant unions are demanding that Mr. Macron abandon his entire reform plan.

Mr Macron's overall plan is to replace the current system of 42 different pension regimes with a single, points-based system that will be the same for everybody.