Russian cosmonauts never had sex in space during the 50 years of human exploration of the cosmos, and rumors about secret sexual experiments were myths, the Interfax news agency reported Friday.

"There is no official or unofficial evidence that there were instances of sexual intercourse or the carrying out of sexual experiments in space," Valery Bogomolov, the deputy director of the Moscow-based Institute of Biomedical Problems, told Interfax. 

"At least, in the history of Russian or Soviet space exploration, this most certainly was not the case."

Rumors have persisted for years of secret Russian and American programs to test the effects of weightlessness on sex, but these were always strongly denied by both sides.

"As for American space exploration, well, I just don't have the information to categorically deny that," said Bogomolov. "There are just anecdotal rumors, which are not worth trusting."