The former head of KSD, a government-linked insurance group under criminal investigation for alleged lending irregularities, has voluntarily visited prosecutors to deny the allegations against him, sources close to the case said Monday.

Tadao Koseki, 79, is under investigation by the Tokyo Public Prosecutor's Office on suspicion of misappropriating several hundred million yen of KSD's funds by lending the money to its numerous affiliates without sufficient collateral.

KSD is a mutual aid society for small businesses under the supervision of the Labor Ministry.