Six banks have sued the firm for nearly 28 billion yen, for issuing false statements after Olympus hid investment losses by disguising them in its accounts.

Olympus’s share price fell by more than 70% in the immediate aftermath of the £1.1-billion cover-up, which was exposed by Michael Woodford, the company’s former British boss, turned whistleblower.

In a statement Olympus said that the ‘impact of this lawsuit [on] the company’s results of operation is unknown at this stage’.

The lawsuit covers the period between the fiscal year 2000 and the first quarter of the 2011 fiscal year.

Last year, former Olympus chairman Tsuyoshi Kikukawa was handed a suspended three-year jail sentence for his part in the scandal.

Kikukawa, along with former executive vice-president Hisashi Mori and Hideo Yamada, a former Olympus auditor, were arrested in connection with a suspected breach of Japan’s Financial Instruments and Exchange Act.

The banks suing Olympus have been named as: Mitsubishi UFJ Trust and Banking Corporation; The Master Trust Bank of Japan; Japan Trustee Services Bank; Trust & Custody Services Bank; The Nomura Trust and Banking Co; and State Street Trust and Banking Co.