A French bill aimed at decriminalizing prostitutes and fining their customers is being turned upside down by the Senate, led by the conservative opposition.

The bill was approved by France's Socialist-dominated lower house of Parliament in 2013 amid heated debate. Supporters argue it would help fight human trafficking networks, while opponents defend those who buy sex.

The Senate is taking up the debate Monday and votes on the bill Tuesday. During preparatory work in commission, senators amended the text to include a ban on soliciting and to remove punishment for customers.

The final vote, in the lower house, could be several months away.

Prostitution is currently legal in France, but brothels, pimping, soliciting in public and the sale of sex by minors is prohibited.