Beijing, Jan 10 (IANS): At least 57 people in China were jailed for confining and forcing 31 people to buy pyramid schemes, said a court.

Prosecutors said the 57 defendants had virtually imprisoned 31 people for over 10 days to force them to buy their pyramid schemes from July 2012 to June 2013 and threatened those who fought or tried to escape, the Shanghai Daily reported Friday.

The 57 defendants were jailed for six to 18 months, the Shanghai No.1 Intermediate People's Court said.

The defendants locked the doors and windows after luring the people inside a room. The victims were not allowed to contact anyone and were guarded by the criminals round-the-clock.

During the confinement, the victims were persuaded to buy the pyramid scheme products and join the organisations which the defendants claimed were funded and supported by the government and would win them high returns.

Some of them eventually agreed to sign up. Others were later rescued by police or escaped on their own.

In another incident in Pudong New Area, 12 criminals confined four people in February and March last year. They forced them to buy "shares" in their pyramid scheme.

One of them managed to escape after he was taken to another room. The others were rescued by police who detained the 12 people March 14. They were sentenced to one year in jail.