Beijing's crackdown on corruption has reached the supposedly non-profit-making China Sexology Association whose business activities have come under investigation, state media said on Thursday.

Founded in 1994 as an academic society studying sexual health products, the association is not allowed to profit from business activities.

"But evidence shows it has taken part in a series of business activities, and has even compiled business contracts where the association can reap as much as 60 to 80 percent of profits from the exercises," the Legal Evening News said.

The association was suspected of setting up an "expert committee" to comment on health products without approval from the Ministry of Civil Affairs, the Beijing-based newspaper said.

"At a sex culture festival held in Guangzhou last month, the association sold copper plates that bore its name to dealers of sex health products," Xinhua news agency said. "The plates were worth 400 yuan (28 pounds) to 600 yuan each."

The association denied wrongdoing. "We welcome authorities to come and investigate," chairman Xu Tianmin was quoted by the Legal Evening News as saying.

"It will get rid of misunderstanding and prove that we are not guilty."

The association was set up to "help promote sexual and reproductive health, to popularize the knowledge of marriage and the family so as to contribute to the building of China's spiritual culture".

Corruption was virtually wiped out in the years after the Communists swept to power in 1949 but has made a comeback alongside market-oriented reforms introduced in the late 1970s.