The raid has been expected to follow a re-statement of Olympus's financial records, which were presented on December 14 and revealed a $1.1 billion dent in its balance sheet after a 13-year fraud.

The planned search by Tokyo prosecutors, likely to be conducted jointly with police and the Securities and Exchange Surveillance Commission, follows mounting allegations that former Olympus executives led the accounting fraud, Kyodo said.

Kyodo cited the sources as saying prosecutors hoped to build cases by the end of March against former Chairman and President Tsuyoshi Kikukawa, former corporate auditor Hideo Yamada, and former Executive Vice President Hisashi Mori.

Former employees at major securities companies could also be implicated for allegedly abetting the fraud, it added.

Olympus, a maker of cameras and medical equipment, spent hundreds of millions of dollars on dubious M&A deals as part of an attempt to hide investment losses from investors for 13 years.

The company last week filed five years worth of corrected financial statements, plus overdue first-half results, just hours before a Tokyo Stock Exchange deadline that could have seen it automatically delisted.

(Reporting by Chang-Ran Kim; Editing by Paul Tait)

• A Permanent Economic Emergency