In December 2013, the lower house of parliament, the National Assembly, approved legislation making clients of prostitutes liable for a fine of 1,500 euros ($1,620) for a first offence and double that thereafter.
But by a large majority, the opposition-dominated Senate reversed the National Assembly's proposal, scrapping the fines for prostitutes' clients and also dropping plans to repeal a law that made soliciting an offence in 2003.
The legislation has already drawn fierce opposition from sex workers, who said it would drive prostitution further underground and make them vulnerable to abuse.
Health Minister Marisol Touraine hit out at the Senate's move, saying: "What happened... Is absolutely unbelievable and contemptuous towards women."
Also Read
Putting the blame on prostitutes rather than their clients is "regressive" and "deprives us of a major tool to reduce demand and therefore prostitution," she added.
Keeping solicitation an offence will "push the women into the shadows and we know it adds to the danger of their situation," said Juliette Meadel, spokeswoman for the ruling Socialists.
According to the interior ministry, most prostitutes are from eastern Europe, Africa, China and South America.
Gregoire Thery, head of a group that urges the complete abolition of prostitution, took aim at the Senate's vote.
"The Senate has chosen to protect the complete impunity of clients and prefers to penalise even further the prostitutes instead of these men," he said.
However, the National Assembly has the last word on the issue and is likely to revert to the original plan of penalising clients.