Tokyo prosecutors on Wednesday arrested three former leaders of the Japan Dental Federation for allegedly falsifying reports of political donations made to a Liberal Democratic Party lawmaker.

The three, including former President Mikimasa Takagi, 70, allegedly tried to cover up donations to a support group for Midori Ishii, making them out to be donations to another lawmaker's group instead. This was done, it is alleged, to prevent donations to the Ishii side from topping an annual limit of ¥50 million.

The federation is suspected of sending ¥50 million to the Ishii group via a group supporting Democratic Party of Japan lawmaker Masami Nishimura in 2013, while contributing another ¥45 million directly to the Ishii group, they said.

Former Chairman Naofumi Tsutsumi, 73, is alleged to have falsely reported ¥50 million in donations to another lawmaker in 2010, while former vice president Yoshinobu Murata, 70, is suspected of involvement in both cases.

From January to March of 2013, Takagi and Murata allegedly disguised ¥50 million in donations to the Ishii group as those to a support group of Democratic Party of Japan member Masami Nishimura. The federation contributed another ¥45 million directly to Ishii's group.

Tsutsumi and Murata are alleged to have reported the federation's donations in May 2010 to Nishimura's group as having been made to a DPJ branch. The DPJ, now the largest opposition party, was then part of the ruling coalition.

Prosecutors raided the federation's office over the 2013 case in April.

Making his first public appearance since a news conference in June, days before stepping down as chairman, Takagi defended the donations as legal.