The contentious public debate around whether to use nuclear power in Japan, in the wake of the 2011 Fukushima disaster, took another major turn on Monday when it was revealed that a former power company official made secret payments to Japanese prime ministers for nearly two decades.

Chimori Naito, the former vice president of Kansai Electric Power Co. (KEPCO), today one of the country's leading providers of nuclear power, has admitted to secretly paying seven of Japan's prime ministers 20,000,000 yen (about $200,000) on an annual basis for 18 years.

The revelation, disclosed to the Asahi Shimbun, sheds new light on what some in Japan have suspected is a cozy relationship between the country's nuclear energy industry and its political leaders.

Former KEPCO vice president Chimori Naito. Image: Asahi Shimbun

Naito, 91, claims he made the payments, which span most the '70s and '80s, to prime ministers Kakuei Tanaka, Takeo Miki, Takeo Fukuda, Masayoshi Ohira, Zenko Suzuki, Yasuhiro Nakasone and Noboru Takeshita.

Of the seven prime ministers, only one, Yasuhiro Nakasone (last in office in 1987), remains alive. When contacted by the paper, Nakasone reportedly did not acknowledge receiving the donations and a current KEPCO official claimed no knowledge of the transactions.

In a series of interviews lasting roughly eight months, beginning in December 2013, Naito laid out the details of his role in facilitating the hidden payments to Japan's political leadership.

Naito says he was eventually compelled to step forward due to the mishandling of the Fukushima incident. "As I began to think about my own death, I also recalled the course I had taken in life," Naito told the paper. "A reporter came just at the time when I began feeling that I wanted to talk about matters I had never spoken about until now. I thought it would serve as a lesson for future generations."

According to the report, such donations were not illegal at the time but were banned by Japanese power companies in 1974. Japan's history of political corruption through corporate donations, and the laws governing such matters, remain a complicated area, filled with loopholes even today.

And while none of Naito's claims touch the current leadership, the disclosure is likely to further intensify the call from a number of local politicians (including former prime minister Junichiro Koizumi) and the public for the country to abandon nuclear energy. Just months after the 2011 accident, anti-nuclear protests became a common sight in Japan, with one of the most recent demonstrations occurring in March this year.

Japanese anti-nuclear protesters rally on the streets of Tokyo on Image: Junji Kurokawa/Associated Press

Japan's current prime minister, Shinzo Abe, is a member of the Liberal Democratic Party, the political party currently pushing for the controversial restart of nuclear power plants in Japan, following widespread nuclear reactor shut downs in the country after the March 2011 accident at TEPCO's nuclear power plant in Fukushima.

In April, just weeks after the second anniversary of the 2011 disaster, the government unveiled a revision to its energy policy, which previously envisioned a nuclear-free Japan by the 2030s. In the new plan the government calls for efforts to "promote reactivation of nuclear reactors." Currently, nuclear power is responsible for roughly 30% of Japan's electrical power.

However, in May, a Japanese court ruled that it would not allow two nuclear reactors operated by KEPCO in Oi, Fukui prefecture to be restarted. The reactors in question, number 3 and 4, where built in the '90s and are at the same facility as two other, currently inactive reactors, originally put into operation back in 1979.

The ruling, brought about by a lawsuit from a group of 189 Japanese citizens, was seen as a landmark legal victory for anti-nuclear voices in Japan and a possible legal precedent for future cases fighting the restart of other nuclear reactors in the country.