Johannesburg - South Africans should take care when choosing investments that offered large returns within a short period, the SA Reserve Bank warned on Thursday. Many of these lucrative options were scams, bank spokesman Hlengani Mathebula said in Johannesburg."Report any suspected Ponzi or pyramid schemes to the SA Police Service or the SARB."Though there were several investigations underway into schemes in KwaZulu-Natal and Gauteng in particular, the central bank regarded this as a national problem."Once you focus on a specific area or name, they move. This is a national issue," Mathebula said."Millions and billions" of rands were lost through pyramid schemes.In 2011, the bank opened 15 new investigations and continued with a further 26.Schemes being probed included Realcor Holdings Pty Ltd, Sharemax Investments, and Ingele Mineral Holdings.In total, the bank had investigated 222 schemes in the past five years.To raise public awareness of the issue, the bank had started a campaign with the slogan, "Beware of oMashayana [con artists]."It would appear on TV, radio, and in the print media.Mathebula said thousands of South Africans lost money every year to illegal deposit schemes, known as Ponzi or pyramid schemes."These schemes hook the public by convincing them of high returns in a short space of time."Instead, the schemes collapsed as soon as they failed to recruit new investors. Pensioners were particularly vulnerable, as were those who received bonuses or had recently received death benefits.Those participating in stokvels, or who had benefited from Road Accident Fund payouts, were also targeted, Mathebula said.The problem cut across all sectors of society, with both the poor and rich falling victim.Wealthy people were frequently motivated by greed, while poorer people were ignorant of the risks, said Mathebula.The bank was usually only made aware of such schemes after people had already lost money, he said.