TOKYO, July 6 (Reuters) - Shares in Japan's Toshiba Corp fell 5 percent in early Monday trade on fears that an ongoing third-party investigation into past accounting practices was finding more irregularities than previously expected.
A source familiar with the matter said on Saturday that Toshiba may need to mark down past earnings by over 100 billion yen ($818 million), more than double earlier estimates.
The Nikkei business daily reported that the newly discovered errors, related to computer parts procurement, could see an earnings mark down of around 150 billion yen.
In a statement on Saturday, Toshiba said it had no information to disclose now, citing the ongoing investigation.
Shares of Toshiba, whose businesses range from laptop computers to nuclear power plants, fell to as low as 402.0 yen in early trade, or down 22 percent since the company disclosed the internal investigation in early April. The Nikkei average was down 1.3 percent.
Toshiba has not been able to close its books for the year that ended in March due to the probe. It has also skipped its year-end dividend to shareholders.
The investigation had previously found inappropriate bookkeeping in areas such as highway electronic toll collection systems, power meters and semiconductors likely led to profits being overstated by nearly 55 billion yen in recent years.
The company has said irregularities found so far included not booking appropriate losses and expenses, as well as underestimating material costs.
The investigation is expected to conclude in mid-July.
The accounting probe is Toshiba's second in less then two years. In October 2013, it announced that it found its medical subsidiary, Toshiba Medical information Systems, had overstated results for several years. ($1 = 122.3100 yen) (Reporting by Ritsuko Ando; Editing by Chang-Ran Kim)