Prosecutors indicted three subsidiaries of non-ferrous metal maker Mitsubishi Materials Corp. and two of their presidents on Sept. 12 over widespread falsifications about the quality of their products.

Mitsubishi Cable Industries Ltd., Mitsubishi Aluminum Co., both based in Tokyo, and Niigata-based Diamet Corp. were charged with violating the Unfair Competition Prevention Law, according to prosecutors of the Special Investigation Department of the Tokyo District Public Prosecutors Office.

Hiroaki Murata, 61, president of Cable Industries, and Mutsumi Yasutake, 60, president of Diamet, were indicted without arrest on charges of conspiring with employees to falsify quality data reports.

Mitsubishi Aluminum President Akio Hamaji resigned on the same day to take responsibility, even though he had remained at the post long after the falsifications came to light.

The indictments of Murata and Yasutake are the first against individuals in a series of quality data falsifications at Japanese manufacturers, including major steelmaker Kobe Steel Ltd., that have been uncovered since last year.

Prosecutors would not say if the two former presidents have admitted to or denied the allegations.

The indictments cover falsified product inspection results that the subsidiaries sent to client companies from 2016 to 2018, prosecutors said.

Their products did not meet specifications agreed upon with their clients, but the inspection results were altered to give the impression that the products had achieved that level of quality.

Such falsifications apparently started decades ago.

Since November 2017, Tokyo-based Mitsubishi Materials has said that quality data falsifications were found at five of its subsidiaries, including the three that were indicted.

The falsifications have continued since the 1970s, and products with faked quality data have been shipped to 825 companies, the company said.

Even after the falsifications came to light, Murata and Yasutake allowed their companies to ship the products while concealing relevant documents, according to prosecutors.

Investigators in July this year searched Mitsubishi Materials and its subsidiaries.

Hironori Miyahara, managing director at Mitsubishi Aluminum, will serve as acting president of the subsidiary for the time being.

Mitsubishi Materials said six of its board members and 11 board members from the three subsidiaries will return 10 percent of their monthly remunerations for October.