An inquiry into the way prostitution is treated in law led by Keith Vaz should be abandoned following allegations he paid for the services of male escorts, a campaign group has said.
Nordic Model Now (NMN) said the claims, made in the Sunday Mirror, amounted to a conflict of interest.
NMN advocates decriminalising prostitutes themselves and making buying sex a criminal offence.
The group has previously voiced opposition to an interim report by the Home Affairs Select Committee, which is leading the Prostitution Inquiry, over recommendations solicitation and sharing of premises by sex workers should be legalised.
NMN said the inquiry should now be disbanded and reformed with members obliged to declare any history of purchasing sex, as well as a mandatory 50 per cent of members being female.
Mr Vaz has called the report by the Sunday Mirror "deeply troubling".