The German team has now turned to generating sperm from very early germ cells taken from testicles.

If it works in the mouse, I'm sure it will also work in the human." - Dr Wolfgang Engel.

Artificial human sperm could come to the aid of infertile men, according to a team of German scientists who have used lab-grown sperm to inseminate mice.

Artificial sperm could also make males totally redundant, permitting women to give birth without a biological male mate.

The genetic scientists at the University of Goettingen in Germany have produced 65 mouse foetuses using sperm which was grown from embryonic stem cells, according to a Deutschlandfunk radio report.

Twelve baby mice have been born using this artificial, lab-grown sperm, said Dr Wolfgang Engel, director of Human Genetics at the medical university.

However, the mortality rate is high, he told the German broadcaster.