Human sperm created in Britain

British scientists claimed Wednesday they have created human sperm using embryonic stem cells, in a medical first that they say will lead to a better understanding of fertility.

Researchers led by Professor Karim Nayernia at Newcastle University and the NorthEast England Stem Cell Institute (NESCI) developed a new technique that allows the creation of human sperm in the laboratory, AFP reports.

Prof Nayernia said the development would lead to a better understanding of why infertility happened in men, and what caused it.

He said: "This understanding could help us develop new ways to help couples suffering infertility so they can have a child which is genetically their own.

"It will also allow scientists to study how cells involved in reproduction are affected by toxins, for example, why young boys with leukaemia who undergo chemotherapy can become infertile for life - and possibly lead us to a solution."

The scientists stressed they had made no attempt to fertilise human eggs with the sperm, The Press Association repots.

But many other British experts say they are unconvinced by the research. They also say the sperm cells created in the laboratory were clearly abnormal, The Associated Press reports.