Schools minister Nick Gibb has said there needs to be improved sex education to teach pupils about HIV and Aids
It is "unforgivable" that many children are not taught about HIV and Aids in school, the schools minister has said.
Nick Gibb said it was a "huge concern" that research has shown that one in four youngsters is not given lessons on the issue.
This is despite lessons on the illness being a compulsory part of the curriculum for secondary schools.
Appearing before a House of Lords committee on HIV and Aids in the United Kingdom, Mr Gibb said: "It is a concern to the Government that there are 83,000 people with HIV/Aids, of whom 4,200 are young people.
"It's a huge concern that the sex education forum reported that one in four children are not being taught about HIV/Aids in schools."
Mr Gibb was asked to address concerns that personal, social, health and economic (PSHE) lessons were in danger of being sidelined as the subject is not part of the Government's review of the national curriculum.
A separate internal inquiry into PSHE, which covers topics such as sex and relationships, is being established with the remit due to be published soon.
Mr Gibb insisted that the PSHE review will be given a high priority, and that while Ofsted had found the subject was taught well in many places, more needed to be done to improve it across the school system.
He said: "When we have a survey which shows that one in four children are not being told, or taught, about HIV, which is a deadly disease that can be simply avoided and simply caught, a lack of knowledge in this area is unforgivable in our school system."
Secondary schools are required to provide sex education as part of their basic curriculum. At a minimum this must include education about HIV/Aids and any other sexually transmitted disease.