The French parliament is debating a bill which would crack down on prostitution by imposing hefty fines on anyone paying for sex.
Prostitution is legal in France but until now only soliciting and pimping were illegal.
Under the bill, those caught paying for sex would face an initial fine of 1,500 euros (£1,250; $2,030).
Meanwhile, a man has reportedly been arrested for the horrific murder of a prostitute in Paris earlier this week.
Critics of the bill say it would drive the sex trade underground in a country which has up to 40,000 prostitutes.
The actress Catherine Deneuve is one of hundreds of celebrity figures urging the government to reconsider.
A similar resolution was voted through the National Assembly at the end of 2011, with the support of both left and right. It only failed to proceed because of lack of parliamentary time.
A new vote is scheduled for Wednesday. The ruling Socialists, with their large parliamentary majority, are expected to vote it through.
According to Le Parisien newspaper, a man arrested on Thursday evening has partially confessed to the murder of a prostitute in the Bois de Boulogne, a park in the city notorious for the vice trade.
The woman's dead body was found on Monday by a walker. Partially burnt, it had knife wounds and the head had been smashed in with a knuckle duster.
The Parisian daily's sources said police had traced a mobile phone found at the scene to the suspect, 21. He allegedly told police officers he had "felt the need to take his anger out on somebody" after recently being made redundant.
Only some 30 members of the National Assembly were present when the debate began on Friday afternoon.
Maud Olivier, the Socialist MP who presented the bill, attacked critics of the ban in her opening speech.
"So is it enough for one prostitute to say she is free for the enslavement of others to be respectable and acceptable?" she asked.
"Where is the glamour in the 10 to 15 penetrations a day undergone by women compelled to be prostitutes, evidently for economic reasons, with dramatic consequences for their health?"
"To say women have the right to sell themselves is to disguise the fact that men have the right to buy them."
Supporters and opponents of the bill held rival rallies near the National Assembly.
There are more than 20 articles in the bill, most of them are aimed at disrupting foreign pimping networks or helping sex workers who want to stop. One article abolishes the existing law against soliciting.
The fine being debated would be doubled for repeat offenders.
Under the bill, clients would be made to undergo an "awareness" course on prostitution, similar to ones on the dangers of drink-driving given to traffic offenders.
France's proposed crackdown contrasts sharply with the situation in Germany, where the stigma has been removed from prostitution.
As a result, there are now some 400,000 prostitutes in Germany, or 10 times the estimated number in France.
Sweden cracked down on clients with a similar law in 1999, since when street prostitution has reportedly fallen sharply in its largest cities. However, street prostitution in neighbouring Norway and Denmark increased.
The Netherlands legalised prostitution in 2000 but campaigners say the measure played into the hands of criminals and human traffickers.
The vast majority of the prostitutes active in France are believed to be foreign nationals.
'We are afraid'
Tim Leicester of the non-governmental organisation Medecins du Monde said he feared the French proposal to penalise paying for sex would actually harm prostitutes.
"That won't change anything for prostitutes," he told the Associated Press news agency.
"They will be forced to continue to hide themselves because even if they are not risking arrest, their clients are. And their survival depends on their clients."
One prostitute, Xiao Chuan, said she feared that clients might want to take prostitutes "to places that are more and more hidden, for example basements, car parks, forests... isolated places that we are afraid of because we won't be secure".
However, Rosen Hicher, a former prostitute who is now an activist, argued that targeting clients was the only way to stop prostitution.
"You need to tackle the root of the evil," she said. "Prostitution is kept up by clients and the only way reduce it - because of course the mentalities need to evolve - the only way to stop it is to punish the client."