The team claimed to have created human sperm from stem cells taken from an embryo which could one day lead to new treatments for infertility in men.
However other scientists in the field remained unconvinced that the cells were proper sperm and the cells had not been used to fertilise an egg.
The claims made headline news around the world after a study by researchers at Newcastle University was published in the journal Stem Cells and Development.
But Graham Parker, editor in chief of the journal, was told three days later that two paragraphs in the research paper had been plagiarised from a 2007 paper in another publication.
