Moscow (dpa) - Rumours that Russian and US cosmonauts have been testing sex in space were denied by Russian officials on Wednesday, news agency Interfax reported.


"There is no proof ... that on any mission cosmonauts had sex," the deputy head of the Institute of Bio-Medical Problems, Valery Bogomolov, told a news conference in Moscow.


"Cosmonauts, too, are regular people, but ... I have not heard about any sex in orbit," he said.


The Russian scientist referred to an experiment conducted by the institute, which researches space health issues by simulating flight conditions on a mission to Mars.


Six cosmonauts, including a woman, had spent two weeks isolated in a zero-gravity capsule, Bogomolov said, but "there were no complaints over the absence of sex."


Speculation over sex in space has been rife since a woman first joined the team of three boarding the cramped Soyuz rocket to the international space station in 1982.


In 1991, US sweethearts Jan Davis and Mark Lee married shortly before their joint space orbit, fuelling rumours in the United States.


The Russian institute appeared to be responding to a document widely circulated on the internet about an alleged 1996 experiment carried out by the US space agency NASA.


The experiment allegedly tested 10 different positions, including the help of elastic bands and other fastening devices, for optimal zero-gravity reproduction.


"We do not have such experiments in our country," Bogomolov said.