Schools should be compelled by law to teach children about issues such as contraception, abortion, sexuality, abuse and sexual consent, a sex education lobbyist will tell MSPs.

Scotland has one of the highest teenage pregnancy rates in Europe and is "rife" with sexually transmitted infections (STIs) and homophobia, while its "ambiguous" guidance on consent "adds to sexual violence, rape and verbal harassment ", according to Sexpression: UK.

The student projects network is urging Holyrood to use legislation to compel schools to provide sex and relationship education (SRE).

Jack Fletcher, of Sexpression: UK and an Aberdeen University medical student, will make the case for statutory sex education at Holyrood's Public Petitions Committee tomorrow. He said: "Although teenage pregnancy has fallen greatly in recent years, the rates in Scotland are still one of the highest in Europe. STIs are still rife due to lack of contraception use. Homophobia is rife in schools and this is an issue that needs effective confrontation, of which education is key."

Mr Fletcher also called for greater education on issues such as consent, online safety, sexual violence, body image and stereotyping.

More than three-quarters of denominational schools will not discuss contraception, even if raised by pupils, while almost as many were unwilling to discuss STIs, said the organisation. Nearly one-quarter of schools have no SRE-trained staff and in more than half of schools the staff responsible for SRE were not trained, it added.

The Scottish Parliament Information Centre has advised MSPs that Scotland has almost no statutory curriculum, with only religious education and Gaelic instruction in certain regions enshrined in law. A spokesman added: "Responsibility for SRE lies primarily with local authorities."