A 98-year-old man has become the oldest person to face trial in China's capital after being charged over an alleged scam to cheat an academic out of over 100,000 dollars, state media reported.

The intricate plot allegedly involved the man, Zhou Zhiping, posing as a well-connected former government official able to access funds frozen from the communists' war with Kuomintang nationalist forces, Xinhua news agency said.

The target of the scam, a 74-year-old American-Chinese man with doctorates in physics and chemistry, was promised 20 million yuan (three million dollars) if he helped finance the unfreezing of the money, Xinhua reported on Wednesday.

The alleged victim, surnamed Chen, paid 749,000 yuan to Zhou and two younger accomplices before realising he had been conned, the agency said.

Zhou went on trial in a Beijing court on Tuesday, becoming the oldest defendant ever in the Chinese capital's judicial system, Xinhua said, adding he faced 10 years in jail if found guilty.

But he reportedly insisted he was innocent.

"I'm not guilty. I won't be jailed," he said in court, according to Xinhua.

It was not clear when the trial would end, or when a verdict would be delivered.

Court officials were not immediately available to comment.