An assembly member has accused a newspaper group of taking advertising income from massage parlours it named as part of alleged sex trafficking.
Lynne Neagle told AMs the advertising was worth £500,000 a year
Torfaen AM Lynne Neagle said Media Wales was guilty of "gross hypocrisy" over a South Wales Echo story claiming 60 trafficked women worked in Cardiff.
Leader of the House Carwyn Jones called on the media group to explain the ads.
Media Wales said: "All advertising across the group complies with ASA regulations and all relevant laws."
The article in the South Wales Echo last week quoted an Amnesty International report which claimed up to 60 women, who had been sex trafficked in to the UK, were working in brothels in Cardiff.
It cited the case of an 18-year-old Lithuanian girl who said she was repeatedly gang raped, beaten and threatened and made to work at three massage parlours in the city.
A leader article in the same edition of the evening paper said the "hideous trade" in sex slavery "must be stopped" and called on "every right-minded citizen" to help police "arrest these vile human traders".
Also in that edition, the newspaper's classified advertising section carried a series of adverts under a column headed "Adult Massage".
Ms Neagle told assembly members that all three parlours the paper had referred to had adverts in that column.
She said: "This advertising, carried through papers with whom we advertise, rakes in roughly half a millions pounds a year for Media Group Wales.
"That makes them, at least in my eyes, the richest pimps in south Wales," she told AMs.
Ms Neagle said she wanted the assembly government to withdraw its advertising through the newspaper group, which she put at £3m a year.
A Welsh Assembly Government spokesperson said: "We are not at present reviewing our advertising policy, but the minister Carwyn Jones said today that we will be looking into it.
"The issue of massage parlours has been raised on the floor of the assembly and we will wait for the newspaper to give its response."