About 30 people filed a police complaint in Bangkok on Wednesday claiming that an online foreign exchange scam had tricked about 1,000 people out of 100 million baht.
One of the complainants, Thasaran Salaylanont, 41, said she and other people had invested in Wealthy-Plus fund, advertised on Facebook and LINE social media systems.
The three people who operated the service promised a 10% return by investing in foreign exchange, and higher gains for clients bringing in new members.
Ms Thasaran said she gradually invested in the fund from June 20, paying in about 180,000 baht in total. She initially received returns, but the Facebook page was closed on July 22.
Members were told that the page would be temporarily shut down for maintenance, she said. They had not been able to contact the operators since.
Members learned later that about 1,000 people had fallen victim to the scam, which involved about 100 million baht in all. The scheme also existed in a neighbouring country, Ms Thasaran said.
They filed their complaint with the Technology Crime Suppression Division at the government complex in Chaeng Wattana.