TOKYO — A former president and a vice president of the Japan units of two major U.S. computer-related firms were found to have evaded 80 million yen and 60 million yen in income tax, respectively, by hiding gains from exercising stock options awarded from their parent firms, sources said.

The Tokyo Regional Taxation Bureau has filed criminal accusations against the two on suspicion of violating the Income Tax Law at the Tokyo District Public Prosecutors Office and the Yokohama District Public Prosecutors Office.

They invested the income they hid in the United States in an effort to prevent the alleged tax evasion from being discovered, the sources said.

One of the accused is Miki Ishii, 46, of Mitaka, Tokyo, who was president of software firm Adobe Systems Inc. Japan, the Japan unit of Adobe Systems Inc. of the United States, from 2002 to 2005.

The other is Makoto Baba, 63, of Kamakura, Kanagawa Prefecture, who was former vice president of personal computer manufacturer Hewlett-Packard Japan, Ltd., the Japan unit of information technology giant Hewlett-Packard Co., from 2005 to 2006.

The cases were the third instance in the nation in which public prosecutors have filed criminal complaints over tax evasion involving stock options.

According to the sources, Ishii and Baba failed to report or underreported gains derived from exercising stock options to tax authorities.

Ishii allegedly hid about 230 million yen in income in the two years until 2005, while Baba was accused of hiding about 150 million yen over a three-year period.

After selling their own companies' stocks obtained through U.S. stock options, they earned only a small amount of money from the gains and kept the assets in the United States.

It is quite difficult for tax authorities to become aware of cases in which Japanese exercise stock options awarded by an overseas parent firm and sell stocks in a foreign country.

Baba did not report at all the income he gained from the stock deals, according to the sources. However, he must have known the income-reporting requirement as he had been previously investigated by tax authorities in an unrelated case, the sources said. In that instance, Ishii only reported part of the gains.

Ishii told The Yomiuri Shimbun that he underreported the income due to calculation errors and revised the report, while an attorney of Baba said he had already paid his tax obligations.