A PYRAMID scheme involving 1.3 billion yuan (US$186 million) is under investigation in northern China, Inner Mongolia police said Tuesday.

Senior executives of an Inner Mongolia forestry company have been detained for alleged pyramid sales of so called "forestry ownership"to more than 30,000 people.

Famous comic playwright He Qingkui was reported to be the image ambassador as well as the honorary chairman of the company. Police alleged he earned more than 6 million yuan from the company.

He was the life partner of famous comedian Gao Xiumin and the senior writer for Gao and comedian Zhao Benshan. Zhao and Gao were once the most popular comic drama team in China and appeared at the Spring Festival Gala every year before Gao died in 2005.

Chen Xianggui, the board chairman, and Liu Yanying, the general manager, allegedly persuaded victims to "buy"28,700-hectare plots of useless poplar forestry using false information and aggressively persuasive techniques.

Police around the country have instigated more than 40 investigations into the scam and caught more than 70 suspects.

Police in Inner Mongolia, where the company is registered, have caught 13 suspects including Chen, Liu and the other two senior executives.

Meanwhile, the company's assets have been frozen. A liquidation procedure at the company's headquarters was completed by the end of last year.

He Qingkui was reported to be unwilling to return the money, police said.

(SD-Agencies)