The public company responsible for Olympic building of facilities and infrastructure, Solideo, subcontracts its work out to other companies, with these sites then inspected.

In June, nine undocumented workers were identified on a site ran by Solideo, with the company responding by terminating the contract of the subcontractor at fault and the construction company that was affiliated.

Solideo strategy director Antoine du Souich said it quickly "took the necessary steps" by terminating the contract.

Paris 2024 Social Charter Monitoring Committee co-chair and trade unionist Bernard Thibault said there was "a great deal of hypocrisy on the part of the political authorities" over the use of migrant workers, calling for better rights for them and more regulation of the construction companies.

"We know that this workforce is essential in many sectors, including construction," said Thibault to AFP. 

"We expected to see what we are already seeing on the construction sites in general and we have had recourse to undocumented workers.

"We can assume that there are others, but on the Olympic sites we have more developed alert and monitoring systems than elsewhere. 

"The challenge is to identify those responsible for the cases already known.

"The large construction groups cannot just pose as victims of unscrupulous subcontractors.

"We can clearly see that there is, sometimes, real arrangements made to derogate from social law, pay less contributions and, ultimately, save money and gain on labour, with the use of these workers who are exploited.

"Yes, we must regularise those who work clandestinely on Olympic sites. 

"Recognising that people who work have equal rights with others should even be obvious."

Mali national Gaye Sarambounou was one of the workers who was kicked off an Olympic building site, but had been working for three months on construction projects for €80 (£70/$87) a day, for between eight and 11 hours a day, without getting paid overtime. 

Under French minimum wage, Sarambounou should be paid €90.16 (£79/$98) a day for eight hours of work.

"I accepted because I know my situation," said the 41-year-old to French news agency AFP. 

"If you don't have papers, you do all the hard work, all the crappy jobs. 

"You have no choice.

"Everyone knows what's going on, but nobody talks about it."

AFP described Sarambounou's living situation as sharing a tiny room with four of his compatriots.

Solideo says its procedures have improved since then.

The CGT union has claimed it is preparing an application for Sarambounou to receive his working papers.