Scientists claim to have found evidence that HIV can be transmitted by sperm.

HIV can be passed on by sperm and not just semen, researchers have claimed.

Scientists at the University of Buenos Aires found that traces of the virus had attached to sperm, suggesting it could cause the infection.

But Dr Stephen Taylor, a leading HIV specialist based at Birmingham Heartlands Hospital, criticised the scope of the research, claiming it was unlikely to apply to "real life".

"The argument over whether sperm is a major factor is a long-standing debate which was very much put to bed, probably about 10 years ago," he said.

"The majority of the evidence suggests that healthy motile spermatozoa themselves do not transmit HIV.

"It is very important to realise that this is an in-vitro model system - a test tube study - which may not relate to what happens in real life at all.

"It may raise some interesting scientific questions but, in real life, I think that the findings aren't going to change very much."