UN rights experts have said they had "credible information" that detainees from minority communities in China may be being subjected to forced organ harvesting, a claim fiercely rejected by Beijing. 

The 12 independent experts, who are mandated by the United Nations but do not speak on its behalf, said in a statement on Monday that they were "extremely alarmed" by the allegations.

Detained members of minority communities appeared to have been forcibly subjected to blood tests and organ examinations such as ultrasound and x-rays, without informed consent, said the UN experts.

This was not something other detainees were required to undergo.

The exam results were then registered in a database of living organ sources for transplants, the experts added.

Liu Yuyin, a spokesman for the Chinese mission in Geneva, condemned the experts for using "disinformation".

"We are deeply alarmed that the special procedure mandate holders in question, lacking rudimentary thinking capability and judgement, have fallen for those clumsy lies," he said in a statement.

UN rights experts had previously raised concerns about alleged forced organ harvesting from prisoners with the Chinese government back in 2006 and 2007, they pointed out.

Beijing had not at that time provided sufficient data on questions regarding the sources of organs for transplants.