Geldof is known for being outspoken

The campaigner, who has three teenage daughters, said the magazines were too explicit for young readers.

"Are they any less offensive than a 22-year-old man going to an 11 or 12 year-old and saying 'I am going to talk to you about sex'," he said.

"If such a conversation happened, you would view it as odd, probably illegal and certainly predatory."

Speaking in a TV interview for the BBC programme Grumpy Old Men, Geldof admitted that he had not banned the magazines from his home but he was still outraged to see their contents.

But he insisted he was not just being an overprotective father and would have been offended by the magazines even when he was younger.

Free condoms

Popular UK teenage magazines including J17, Sugar and Mizz often contain articles about love, sex and relationships.

J-17 promised to teach girls "how to make boys go crazy about you", while Sugar controversially advertised free condoms for its teenage readers.

Cosmo Girl, aimed at 13 to 17-year-olds, recently published a sealed guide to sex, promising to "answer all the questions they don't teach you in sex education".

But Cosmo Girl editor Celia Duncan has defended its contents, saying it always discussed sex in responsible manner, informing readers rather than promoting sex.

She said: "We work to a very clear set guidelines issued by The Teenage Magazine Arbitration Panel [the industry's self-regulatory panel] and all our agony aunts are trained counsellors - you're not just talking to anyone.

Teen pregnancy

"In fact, our sexual health expert is a trained Childline councillor - it's very important that they are well trained, experienced people dealing with these issues."

She added that the magazine went a long way to prevent girls feeling abnormal if they did not have sex, and that over-16s should be fully educated about sex if they are to make informed choices.

Ms Duncan also said that open discussions about sex could help cut the rate of teenage pregnancies and sexual diseases.