Teenagers want all secondary schools to have compulsory classes with specialised teachers who can openly discuss sex and relationships, a survey released yesterday shows.

The results were compiled from a petition, signed by more than 2,000 teenagers and delivered to Downing Street yesterday, demanding that all schools make sex and relationships education (SRE) mandatory.

It also called on the government to assess secondary schools on the life skills they equip pupils with, and not just GCSE results.

Celia Duncan, the editor of CosmoGirl magazine, which was behind the petition, said one-third of the teenagers thought their SRE was "absolute rubbish" and 81% thought SRE in their school could be improved.

Ms Duncan was joined at Downing Street by 16-year-old Bethany Cole, who was inspired to join the protest after a friend at a Catholic school was denied SRE.

Although there was still significant work to be done, Ms Duncan was optimistic that the views and wishes of teenagers on the SRE issue would guide government policy.

Ms Duncan said: "I believe we are going in the right direction, we just have to keep pushing because the support is definitely there from parents."

Figures released last week using 2004 statistics for England and Wales revealed a 6% drop in unplanned pregnancies in girls under 16, and a 1% decrease in girls aged 18 and under.

Jan Barlow, the chief executive of the sexual health charity for teenagers, Brook, said: "These figures show that real progress is being made in helping young women avoid unplanned pregnancies. I urge the government to ensure that the principle of confidentiality is protected when it publishes its revised guidance on safeguarding young people.

"We also need to ensure every young person is guaranteed comprehensive sex and relationships education in school, as a compulsory part of the national curriculum."