French authorities opened an investigation after an aide of President Emmanuel Macron was caught on video beating a protester during the country’s May Day demonstrations.

Paris prosecutors announced their probe into Alexandre Benalla on Thursday amid a public outcry over the incident on May 1.

Released by the Le Monde newspaper, the video shows Benalla wearing a police helmet dragging a woman away and then hitting a young protester and stomping on his stomach.

Macron’s spokesman on Thursday called Benalla’s behaviour “unacceptable”.

“[Benalla] had been given permission to witness the demonstrations only as an observer,” Bruno Roger-Petit said in a video statement. “Clearly, he went beyond this.”

🔴🔴🔴🔴 ALERTA VIOLENCES POLICIÈRES DES POLICIERS TABASSENT ET GAZENT TOUT LE MONDE PLACE CONTREESCARPE !!

FAITES TOURNER IL FAUT QUE TOUT LE MONDE VOIT !!#ViolencesPolicieres #1erMai pic.twitter.com/Dabr6HHwyJ — Taha Bouhafs 🔻 (@T_Bouhafs) May 1, 2018

Macron has drawn criticism because the incident wasn’t reported to law enforcement authorities. After a 15-day suspension in May, Benalla was brought back onto the president’s security team.

“This video is shocking. Today, we have the feeling that in Macron’s entourage one is above the law,” Laurent Wauquiez, president of the conservative Republicains, told Europe 1 radio.

Far-left leader Jean-Luc Melenchon told reporters: “If we accept that anybody can be a policeman alongside the police, then we no longer have the rule of law.”

On a trip to southwestern France on Thursday, Macron declined to answer questions from reporters on the incident.

Asked if he had confidence in his security officer, Macron on Wednesday pointed at a member of his entourage and said, “He is my bodyguard.”

Labour unions hold demonstrations every year on May 1 in France, and clashes with police are not uncommon.