TOKYO (AP) -- Sanyo Electric Co. said Friday it was fully cooperating with an investigation by securities authorities into suspected window-dressing of earnings at the struggling Japanese electronics maker.

Company spokesman Ryo Hagiwara said an investigation was under way but declined to confirm a report Friday in Japanese newspaper Asahi Shimbun that Sanyo may have falsified its fiscal 2003 earnings report. He would not elaborate.

The Asahi said Sanyo may have written off far less losses than its subsidiaries had, and the Osaka-based company may have falsely reported a profit when it was in the red.

Sanyo shares plunged 17 percent to 190 yen ($1.56) in Tokyo morning trading on the Asahi report.

Securities and Exchange Surveillance Commission spokesman Noboru Takayama declined comment, saying the watchdog does not comment on ongoing individual cases.

The Asahi said Sanyo had written off losses of 190 billion yen ($1.6 billion) at its subsidiaries but reported the losses as 50 billion yen ($412 million).

Such differences have been corrected over the years, and the company's recent earnings reports are not false, the report said.