A controversial US campaigner against pre-marital sex made "unacceptable" claims that contradicted medical fact when she addressed about 150 secondary students in Paisley, sexual health campaigners have claimed.
Pam Stenzel appeared at St Andrew's Academy last month in an event organised by the parent council for S3 students and above. It was also attended by teenagers from other Catholic schools.
A Freedom of Information request to Renfrewshire Council sought clarification on claims apparently made by Ms Stenzel, including that condoms are often ineffective against HIVAids and that 30 per cent of sexually transmitted diseases, including gonorrhoea, are incurable.
Paul Braterman, a University of Texas emeritus professor of chemistry and leading member of Secular Scotland, asked if the council was aware that Ms Stenzel would "depart considerably" from received medical opinion.
He cited a failure to mention Pap smears' effectiveness in counteracting cervical cancer, and Ms Stenzel's "gross misrepresentation" of the HPV vaccination in stating that it is effective for only four of 18 HPV strains, without mentioning its specific use for strains that cause cervical cancer.
The council response said that the school's head had not seen a script before the event and did not know all the specific issues that would be raised.
Will Harris, a spokesman for the Terrence Higgins Trust, said: "These claims show a wilful misrepresentation of the data, with the apparent aim of causing as much panic as possible."
Dr Audrey Simpson, Family Planning Association acting chief executive, said: "It is unacceptable that schools chose to invite a speaker who has clearly given out inaccurate and misleading information. While abstinence can be a positive option for young people, research clearly shows that abstinence-based education does not work."
A Renfrewshire Council spokesman said materials by Ms Stenzel had been used in Scottish Catholic schools for years, and her talk on celibacy before marriage was in line with Catholic schools' "Called to Love" relationships education programme.
Michael McGrath, director of the Scottish Catholic Education Service, said: "The broad thrust of Pam Stenzel's talk was to help young people to realise that the only way of keeping yourself 100 per cent safe from sexual infection was by abstaining from sex until marriage and remaining faithful within marriage."
TESS contacted Ms Stenzel for comment but received no reply.