Thirty investors filed a suit Monday seeking around ¥610 million in damages from Democratic Party of Japan President Banri Kaieda for his alleged misleading investment advice that led them to heavy losses.

In the damages suit filed with the Tokyo District Court, the plaintiffs claimed they relied on published advice by Kaieda when he was an economic commentator that led them to invest in the cattle breeding schemes of farm chain Agura Bokujo, which went bankrupt in 2011.

His advice, including in books and magazines published in the late 1980s and early 1990s, described such investments as risk-free, the suit said.

Kaieda also made speeches at events sponsored by Agura Bokujo to promote the investments, it said.

The plaintiffs, aged between 44 and 78 from 11 prefectures, said Kaieda failed to explain the investment risks and served as the cattle farm chain's promoter.

"As his book described the investment risks as zero, I dialed a phone number in the book to invest," a male plaintiff in his 40s told a press conference. "Kaieda should face the consequences."

During civil conciliation procedures prior to the suit, Kaieda's side denied he was liable.

His lawyer said he will consider the details of the suit after receiving it.