A top security officer for French president Emmanuel Macron has been detained and is being questioned by authorities after he was caught on camera beating a protester.

The president’s office has begun the process of sacking Alexandre Benalla following a public backlash after the May Day footage emerged.

The newspaper Le Monde identified Benalla as the man in the video who was wearing a police helmet and beating a young protester.

Questions about whether Mr Macron’s cohorts are above the law were raised in the French parliament on Thursday.

Mr Macron and BenallaMoves are under way to sack Benalla, officials said (AP)

The presidential Elysee Palace said Benalla had been authorised to follow police operations as an observer on his day off. He was suspended for two weeks and given a desk job, but was allowed to maintain his office at the presidential palace.

A video of the May 1 event in Paris shows Benalla, in a helmet with police markings and surrounded by riot officers, brutally dragging away a woman from a demonstration and then repeatedly beating a young man on the ground. The man is heard begging him to stop.

Another man in civilian clothing had pulled the young man to the ground.

Police, who had pulled the man from the crowd before Benalla took over, did not intervene, and Benalla then left the scene.

Benalla and Mr MacronBenalla was seen in a video wearing a police helmet and beating up a student protester in May (AP)

The second man was apparently a gendarme in the reserves who Le Monde said had worked with Benalla in the past.

Mr Macron was slammed for keeping Benalla on the job two and a half months after the May incident.

A judicial official said Benalla is being questioned on an array of counts ahead of potential charges. Among the counts is violence committed in a group by a person with a public service mission.

The judicial official said the gendarme was detained hours later.

An official at the presidential palace confirmed press reports that the process of sacking Benalla from his job had begun and that Mr Macron’s office had new elements in hand justifying the decision, notably Benalla’s possession of a document from police headquarters that he was not authorised to have, procured in an effort to prove his innocence.