Updated

The editor of a scientific journal that published a controversial paper claiming to have created human sperm from embryonic stem cells for the first time has retracted the study.

Scientists at Britain's Newcastle University reported they had produced the sperm in a laboratory and that it could one day help infertile men father children. Critics said the sperm did not have the specific shape, movement or function of real sperm.

Graham Parker, editor of Stem Cells and Development, says on the journal's Web site that the sperm study "is being retracted," without explaining why. But the scientific journal Nature quoted him as saying on Thursday that the study was retracted because two paragraphs in its introduction had been plagiarized.