Tax authorities have found Olympus Corp. failed to declare about ¥10.3 billion in taxable income in connection with transactions between its group companies in Japan and Britain during a five-year period through March 2011, sources said Thursday.

While the Tokyo Regional Taxation Bureau levied about ¥4.9 billion in back taxes, the actual amount of tax to be shouldered by Olympus is estimated at around ¥1.47 billion, excluding the amount paid in Britain, the sources said.

The Japanese maker of cameras and precision instruments said the export of medical equipment, including endoscopes from its Tokyo-based subsidiary Olympus Medical Systems Corp. to group firm KeyMed Ltd. in Britain, was regarded as a problem.

The bureau is believed to have determined the maker transferred abroad income that was taxable in Japan, as the price of the equipment was lower than that in ordinary transactions, it said.

Olympus said it does not agree with the bureau's decision and will file an objection.