A Beijing judge sentenced 91 people on Sunday for their involvement in a multinational telephone scam that targeted elderly Chinese.

The trial is the first following a joint crackdown by police in China and Southeast Asia, including Thailand, Indonesia and Malaysia.

Prosecutors said the defendants were part of a gang working out of Indonesia that posed as court and police officials to dupe Chinese victims.

"These convicts have damaged the image of (China's) judicial bodies ... by posing as government workers to commit fraud," said Jia Liying, the presiding judge at Chaoyang District People's Court.

Their sentences ranged from 18 months to eight years in prison, along with fines of 2,000 to 8,000 yuan ($320 to $1,285).

According to the court, the defendants, who were all arrested in Indonesia in June 2011, are poorly educated and come from the Chinese mainland, including Sichuan, Hainan, Hunan and Fujian provinces. Fifty-nine of the 91 defendants are women, and the youngest is 20 years old.

Sunday's verdict closed part of a case that involved almost 600 suspects, including 186 from the Chinese mainland, who were arrested across Southeast Asia.

The defendants were divided into seven groups to be sentenced in line with their level of involvement.

Peng Farong, a 29-year-old farmer from Fujian, received the heaviest penalty, eight years in prison and an 8,000 yuan fine.

He and eight others were tried as leaders of the Indonesia operation, which ran from March to June 2011, and is believed to have defrauded victims of more than 2.4 million yuan.

However, Jia conceded that none of the nine are believed to be a senior figure in the pan-Asia operation.

Li Yanling, from Hubei province, said she received a call in May 2011 from a woman who identified herself as a Hubei court officer, claiming she had been summoned over 7,000 yuan in credit card debt.

When Li disputed the claim, she was transferred to another person who said he was a police officer named Jin Dazhi.

"He asked me to transfer money to another bank account because my credit card information and identity card had been compromised," she said.

Li initially transferred 299,000 yuan to an account number provided by Jin, along with another 50,000 yuan at a later date.

Prosecutors said the Indonesia operation may have netted more than 10 million yuan.

"I hope the case was tried in an open way that can alert more residents of such frauds," Jia said, adding that the majority of victims were elderly and retired women.

Zhang Shiting, 41, a convict from Henan province, was sentenced to seven years and fined 7,000 yuan. He said he will appeal the verdict.

Speaking after the trial, he claimed he was hired in March 2011 by a Chinese agent for a job in Indonesia that paid 5,000 yuan a month. However, when he arrived in the country the following June he was taken to a two-story building where he was trained to defraud people.

There was a long script, "but I couldn't remember it", said the father of two, who added from that point he worked as a cleaner.

"No one could leave the building, and the employers took my passport."

Jia said people should confirm information face-to-face with police and never believe messages or calls from strangers claiming to be judicial officers.

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