Olympus Corp. said Monday its group firm in China was involved in wining and dining a customs official as well as giving gifts to the person but said no illegal act such as bribery had occurred.

An internal investigation found that an employee of Olympus (Shenzhen) Industrial Ltd. had spent between 6,000 and 7,000 yuan on such activities, and in 2015 asked the firm to cover the expenses, the Japanese optical equipment firm said.

The investigation also discovered that other group firm employees had engaged in similar practices for other Chinese officials.

Olympus described the case only as a matter of "internal control."

The investigation came after Chinese customs audited the subsidiary in China in 2006 over the number of digital cameras on stock and found there were problems with the figures. The issue was resolved after consultations with Chinese authorities and the company was not fined, according to Olympus.

But in 2014 the subsidiary paid 2.4 million yuan to a consulting firm for the advice it received for consulting with the customs. An investigative panel set up by Olympus in February last year found no evidence that the consulting firm had bribed the customs, Olympus said.