But for the first time, scientists targeted the protein itself and discovered they were able to increase the quantities within infertile so as to successfully fertilise female eggs in the lab.

They say the findings indicate that this form of infertility can be treated with medication, potentially allowing previously infertile men to conceive naturally.

The research team from Qatar University found that injecting the amount of C zeta protein commonly present in infertile men into mouse eggs resulted in no fertilisation, but that they were able to increase the amounts of the protein to trigger a normal fertilisation process.

"Our ultimate goal is to use the tools that we are currently developing not only to treat, but also diagnose, the cases of male infertility associated with absent or dysfunctional PLC-zeta protein in human sperm,” said Dr Michail Nomikos, who led the research.

"We believe that our research can eventually give hope to many infertile couples in the near future.”