The Securities and Exchange Surveillance Commission has searched locations related to Thai-based investment fund Asia Partnership Fund Group over its unit's alleged fictitious investment in a listed Japanese company, according to sources.

The company, Showa Holdings Co., was also raided by the security industry watchdog. The firm, formerly known as Showa Rubber Co., privately issued shares worth about ¥1.2 billion to an APF unit in June 2008.

The following month, Showa Rubber purchased a debt instrument worth about ¥1.1 billion from another APF unit and made an investment in the group's operations, according to market sources, raising suspicions that the share issue may have been a fictitious deal violating the financial instruments and exchange law.