This was revealed in a Democratic Party press conference attended by victims who called on police to properly investigate their cases.

The victims included the mainland housewives of Hong Kong residents who had just arrived a few years ago, pensioners and middle- aged jobseekers.

All said they were duped into buying hundreds of thousands of dollars worth of aroma products.

Cheung, in her 40s, said she was persuaded in 2005 by a neighbor to buy HK$500,000 worth of essential oils of a certain brand after being promised amazing returns.

She said she attended day-long meetings at a company office, during which she was subjected to a variety of underhand sales techniques.

"They told me I must not tell my relatives about the business, otherwise they will stop me. I followed the advice and secretly used the savings held jointly with my husband."

Cheung said relations with her husband had deteriorated since then.

Even her son became a victim, with the woman saying she was stunned to find out he lost HK$67,000 in a fishball selling scam.

It happened when her son was 18. The sum actually came from her. A schoolmate had lured him to join the "business," Cheung said.

Another woman, surnamed Tsang, invested HK$1 million by mortgaging her property.

"My husband was a public security officer and told me it was a scam. I refused to believe him. I said they held grand conferences at the Hong Kong Convention and Exhibition Centre and that the company hired a lawyer to explain its business was legal and profitable."

Mainlanders were also victims of the scam.

Pang from Shenzhen borrowed HK$67,000 from relatives using different excuses, but the money was for seven bottles of essential oils and a membership fee.

"We mainlanders believe too much in the legal system in Hong Kong." Pang said. She earns more than 1,000 yuan (HK$1,116) a month but is now heavily in debt.

The victims later went to police headquarters to meet officers from the Commercial Crime Bureau.

Democratic Party chairman and lawmaker Albert Ho Chun-yan said the total losses involved may rise to HK$7 billion if mainland and Taiwan victims are included.

The company involved in the alleged pyramid selling scam could not be reached for comment.