Kin Cheung-file, File, Associated Press
In this Jan. 3, 2011 file photo, a worker cleans the road outside Khalifa sport complex in Doha, Qatar. The 2022 World Cup host nation announced on Thursday, March 19, 2015 that the final World Cup game of the 2022 tournament will be on Dec. 18.

PARIS — Accusing it of practicing "modern slavery," a French campaign group has filed a legal complaint against construction giant Vinci for grave mistreatment of migrant workers in Qatar, the host country of the 2022 World Cup.

Vinci says it "totally refutes" the charge and will file a counter-suit against the group, Sherpa, for libel.

Sherpa's complaint, if acted upon by French prosecutors, could pressure Qatar and companies engaged there to improve conditions for guest workers.

Sherpa says the suit, lodged Monday, targets Vinci's construction wing and French managers of its Qatari subsidiary and accuses them of driving workers into forced labor and bondage.

Vinci responded with a statement denying the charges and inviting Sherpa to visit its construction sites.