Investment fund mogul Yoshiaki Murakami and three of his executives are expected to be arrested as early as Monday for alleged insider trading, sources said Sunday.

The Tokyo District Public Prosecutor's Office is alleging the Murakami fund violated the Securities and Exchange Law in connection with purchases of shares in radio station Nippon Broadcasting System Inc. from late 2004 to early 2005, according to the sources.

Murakami denied the allegations when he was questioned by prosecutors, the sources said.

"We had our corporate lawyers check the trading not to incur suspicion of insider stock trading, and I thought there was no problem," Murakami was quoted as telling investigators.

The Tokyo prosecutors' special investigative squad will arrest the fund officials if it gains approval Monday from the Supreme Public Prosecutor's Office and the Tokyo High Public Prosecutor's Office, according to the sources.

The Murakami fund, which had actively purchased Nippon Broadcasting shares, allegedly boosted its stake in the radio station based on advance knowledge that Internet firm Livedoor Co. would buy up shares.

Murakami was directly informed by then Livedoor President Takafumi Horie of his decision to join the Murakami fund in efforts to buy the shares before the Livedoor board approved the decision on Feb. 8, 2005, the sources said.

Horie, a friend of Murakami's, began to buy Nippon Broadcasting shares in small lots from around fall 2004 and told Murakami of this, the sources said.