Serious Fraud Office (SFO) has launched a formal investigation into more than $1bn (£634.3m) of obscure payments and acquisitions made by Japan's Olympus Corp., a source familiar with the matter said.
The source declined to be named, and the SFO did not provide an immediate comment.
However, leading lawyers had expected the SFO to team up with prosecutors from the U.S. and Japan in part because one of the hefty payments was linked to the 2008 purchase of UK company Gyrus.
Olympus's former chief executive Michael Woodford, a Briton who fled Japan around a month ago after blowing the cover on around $1.3bn in unexplained fees and non-core acquisitions, promptly handed reams of documents to the agency.
He also contacted the U.S. Federal Bureau of Investigation (FBI), the Department of Justice (DoJ), the Securities and Exchange Commission (SEC) and couriered documents to Japan's Security and Exchange Surveillance Commission (SESC).
Olympus new President Shuichi Takayama admitted last week the company hid losses on securities investments for two decades.