French police brutality
A Video showing a policeman beating up a black woman and spraying tear gas into her face during an arrest was posted online (YouTube)

French authorities have opened an investigation, after a video showing one officer beating up a black woman with a baton and spraying tear gas into her and another woman's face during an arrest was posted online.

Uploaded on YouTube under the headline "Shame to French police", the eight-minute video recorded in Joué-lès-Tours, just outside the central town of Tours, has been watched more than 600,000 times in less than 48 hours, sparking outrage across the country.

"I watched the video and a probe has already been launched," interior minister Manuel Vallas told RMC radio. "There is no place for violence in the police."

Recorded from a balcony in the Rabière suburb the footage shows two policemen trying to hold a man and a woman to the ground.

The four are seen grappling in the middle of the street. During the scuffle the woman somehow trips one of the officers.

The policeman reacts furiously, pulling out his baton and striking her repeatedly with blows to the head and body, as she is a prostrate on ground and even after she moves away.

The policeman then rushes to his patrol car, takes a can of tear gas out of trunk and sprays it in her face. He then chases down another woman who was watching the scene and sprayed her in the face as well after shouting her to back off.

The policeman is hear as calling the women "b***h" and "s**t" several times.

The first woman is left on lying on the ground for a few minutes until reinforcements arrive and she is dragged into a police vehicle. Meanwhile the other officer has managed to restrain the man and force him inside the police car.

The brawl reportedly begun after the man refused to undergo an alcohol test. The officer stopped his car for he was driving erratically.

According to La Nouvelle République newspaper seven people were on board, including the two women.

One of the passengers reportedly attempted to bite the policemen and stole their radio.

The driver was later taken to a hospital and was found high levels of alcohol in his blood.

The video sparked a wave of furious comments against security forces on Twitter under the hashtag #bavure, a term indicating police misconducts.

Police violence against ethnic minorities is a sensitive issue in France, especially in the cities' deprived suburbs or banlieues that are home to a high population of second-generation immigrants and often witness scenes of unrest.

"I don't accept the words 'shame to French police'. It isn't the entire French police force to be concerned here," Vallas said.

"Police should be beyond reproach, and the vast majority of police officers do a difficult and remarkable job."