A French engineer had his testicle amputated by doctors after being clubbed in the groin by truncheon-wielding riot police last week, and now plans to file a lawsuit.

The 26-year-old, identified in the French press as Ivan S., had been taking part in a huge demonstration in Paris over the government's pension reform plans.

More than 1 million people marched in cities around France on Thursday, with the incident occurring during a spurt of violence at a mostly peaceful march in Paris.

Ivan S. said he was knocked to the ground, allegedly by an officer, while taking photos during a confrontation between some demonstrators and police. Another officer charged at him and quickly planted his club in the man's groin. 

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Footage of the incident circulated on social media and French television over the weekend, appearing to confirm his description of the events. Outrage over the incident grew, and Ivan S. was not arrested.

In at least two clips, a man holding a camera is seen falling backwards off a curb and into a road, where several other protesters are standing. An armed officer is seen running after him, raising his arm, and landing a blow with his baton.

Speaking to Liberation, who identified him, Ivan S.  said the officer 'jumps with all his weight right next to [him] and, at the same time, gives [him] a big blow with his truncheon [at] crotch level'. The incident was caught on live television at the time.

As a result of the strike, Ivan S. – a Franco-Spanish engineer – said doctors had to amputate his right testicle.

'When I arrived [to hospital] my testicle was the size of a tennis ball,' he told the French newspaper in an interview, published on Sunday.

'They told me they were going to operate on me, and when I woke up they told me, "The operation has [gone] very well, we amputated your right testicle."'

His lawyer Lucie Simon confirmed that a legal complaint was being filed for 'willful violence by a person holding public authority resulting in mutilation', BFMTV said. 

'It was such a strong blow that he had to have a testicle amputated,' Ms Simon said, adding that the engineer was still in hospital, when speaking on Sunday.

'This is not a case of self-defence or necessity. The proof is in the images we have and the fact that he was then not arrested.' 

The engineer, who lives on the French Caribbean island of Guadeloupe, 'is still in shock and keeps asking why [he was wounded]', the lawyer added. 

Ivan S. told the newspaper he was suing 'so that this stops, because I'm not the first person to be subjected to violence by police'.

Paris Police Chief Laurent Nunez ordered an inquiry into the exact circumstances of the incident as outrage grew over what appeared to be a new case of alleged gratuitous violence by French police, a longstanding complaint.

The police officer has not been identified.

French government spokesman Olivier Veran said in an interview on Sunday on French news station BFM TV that he was neither part of the police or judicial establishments, but 'my thoughts are obviously with this person'.

He said he had 'a lot of empathy' for Ivan S., but stressed the need to 'understand the context' even if 'when we look at the image we are necessarily challenged'.

French law enforcement agencies have long been peppered with excessive use of force complaints. Police unions contend their members often are the victims of violence committed by some people they are meant to protect.

The 2020 beating and clubbing by three police officers of a Black music producer, Michel Zecler, as he left his Paris studio was a catalyst for limited reforms.

The most recent change was the appointment last year of a magistrate to head a unit that investigates allegations of police abuse. Police officers previously led the unit.

French President Emmanuel Macron ordered changes in 2021, saying that 'we have nothing to fear from greater transparency'. That same year, French lawmakers passed a 'global security' law reinforcing certain law enforcement powers. 

The most controversial article, which initially limited video or other images of security officers, was watered down to make it a crime to identify security officers 'with the manifest goal of attacking their physical or psychological integrity'.

Thursday's incident came before another involving police, in which two officers were arrested after shooting dead a man near the near the Place de la République in Paris.

He was shot dead on Sunday evening, with reports saying he was hit by four bullets: a single shot by one officer and three for another. The two officers were taken into custody on Sunday, and an investigation has been launched.

The interior ministry said 80,000 people marched in Paris on Thursday, as part of nationwide protests against President Emmanuel Macron's plan to extend the retirement age from 62 to 64. The hard-Left CGT union however said it counted 400,000 protesters in the French capital.

Across the country as a whole, more than 1.1 million people took to the streets on Thursday. Some unions said more than two million people participated.

Around the Bastille area of Paris, some demonstrators hurled bottles, bins and smoke grenades at police, who responded with tear gas and charged to disperse the troublemakers, according to journalists at the scene.

Taken aback by the size of mass protests against its pension reform, the French government on Friday hinted it was ready to compromise on the unpopular plan but vowed that its core measures would remain intact.