TOKYO: Japan’s Toshiba Corp may need to mark down past earnings by over 100 billion yen ($814 million), more than double earlier estimates, after an investigation into past accounting practices found more irregularities, a source familiar with the matter said on Saturday.

The Nikkei business daily reported earlier on Saturday the newly discovered errors, related to computer parts procurement, could see an earnings mark down of around 150 billion yen at the industrial conglomerate.

In a statement, Toshiba said it had no information to disclose now, citing the ongoing investigation.

The company has not been able to close its books for the year that ended in March while a third-party committee reviews its past bookkeeping practices in a probe prompted by regulators. 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 metres 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.

Shares of Toshiba, whose businesses range from laptop computers to nuclear power plants, have fallen 17 per cent since the company disclosed the internal investigation in early April.

The current accounting investigation is Toshiba’s second in less than two years. In October 2013, it announced that it found its medical subsidiary, Toshiba Medical Information Systems, had overstated results for several years.

Previous accounting investigations in Japan have included camera and medical equipment maker Olympus Corp’s 13-year cover-up of $1.7 billion in losses.