TOKYO (Kyodo) -- Japan's securities watchdog said Monday it has filed complaints with prosecutors against a judge, a Tokyo Stock Exchange official and the official's father on suspicion of insider trading.

The Securities and Exchange Surveillance Commission identified the three individuals accused of violating the Financial Instruments and Exchange Law as Soichiro Sato, a 32-year-old judge temporarily assigned to the Financial Services Agency, former Tokyo Stock Exchange employee Keito Hosomichi, 26, and his 58-year-old father, Masato Hosomichi.

The judge and the TSE employee admitted to the allegations, and Tokyo prosecutors are preparing to indict the two without arrest, a source familiar with the matter said.

Sato is suspected of using information about unannounced tender offers by multiple companies to purchase 11,800 shares in 10 companies, worth approximately 9.5 million yen ($61,000), under his own name from April to September while working at the agency, the commission said.

In Japan, young judges are sent to administrative agencies to gain experience in various fields.

The securities watchdog alleges that Keito Hosomichi repeatedly leaked information about firms' unannounced takeover bids to his father between January and April. His father is suspected of using the information to purchase 15,200 shares in three companies for roughly 17 million yen.

Japan Exchange Group Inc., the parent company of TSE, said it dismissed him in a decision dated Monday.

It also said it will work to restore trust by ensuring employee compliance and improving its internal oversight systems based on the findings of an investigation by the watchdog.

The TSE is Japan's largest securities exchange, with over 4,000 listed companies.