An international trial of a male birth control injection has failed due to its serious side effects, the professors overseeing the German implementation of the test announced Monday.

The trial, conducted by the World Health Organization (WHO) and CONRAD, a non-profit organization aimed at improving reproductive health, began late 2009 and involved 400 people in eight countries.

"The study was ended in March, because the injection does not work in its current composition," said Michael Zitzmann of the University of Muenster, in northern Germany.

One in ten men experienced side-effects including depression, weight gain, increased libido and acne. The older the trial person, the worse the symptoms were. These side-effects had not emerged in earlier national tests of the drug.

"It worked for 90 per cent of the men, but a 10-per-cent (failure), that is simply too much," Zitzmann said.

The trial involved men aged 18 to 45, including around 100 in Germany, living in a long-term partnership with women who had also agreed to the study.

"The expectations were not met," said Hermann Behre of the University Clinic in Halle, eastern Germany. The complete trial results are due to be presented in October, he said.

"But we can already assume that it will not work in this form," Bahre added.

Every eight weeks the men were given a testosterone injection, consisting of drugs that are already used to treat other conditions.

The injections stopped the men from producing testosterone, with the consequence that they also stopped making sperm.

"We need to start from scratch, the result is open," said Zitzmann. He did not think that a male contraceptive injection would be marketable in the next five years.

The pharmaceuticals industry has shown similar scepticism. A research project into male hormone injections by Schering, which first marketed the female contraceptive pill, was ended when they were taken over by Bayer in 2007.

"In the next 10 to 15 years there are no market opportunities for this," said Friederike Lorenzen of Bayer HealthCare Pharmaceuticals in Berlin.

The German association of Research-Based Pharmaceutical Companies VFA says their 43 members are not investigating male contraceptives.

Nevertheless, Behre said success for male contraceptive injections was closer than many thought.

"In China, this kind of testosterone injection was tested successfully on more than 1,000 men. We have had the results since 2009," he said.

Male contraceptives were not aimed at replacing the female pill, Behre added. Rather, they would enable couples to share the responsibility of birth control.