Nikko Securities Co.'s head office in Tokyo was raided Sept. 25 by prosecutors and members of the Securities and Exchange Surveillance Committee in connection with the brokerage's suspected illegal payoffs to "sokaiya" corporate extortionist Ryuichi Koike.

The home of Nikko President Kichiro Takao was also searched.

In a related development, informed sources revealed that a Nikko vice president may have been involved in the brokerage's alleged companywide scheme to provide some 14 million yen in payoffs to Koike. The Tokyo District Public Prosecutor's Office and the SESC suspect that a former general affairs section chief, who maintained close ties with Koike, routinely reported the illicit payments to the vice president, the sources said. Neither individual was named.

The vice president was responsible for Nikko's in-house probe into the illegal payments to Koike after the scandal broke, the sources said. Authorities have already questioned the two, the sources said.

Nikko is believed to have transferred profits earned in stock trading on its account to a Koike-linked account on several occasions in 1995 and afterward, with the total amounting to about 14 million yen. Koike opened an account at Nikko's Ginza branch in June 1992 under the name of Kojin Building Co., a real estate firm run by his brother, and spent 500 million yen to buy shares in Tokyo Electric Power Co., according to the sources.

But he lost about 200 million yen by the end of that year due to a plunge in the stock price and issued a demand to the general affairs section chief that Nikko cover the loss, the sources alleged. Koike continued to demand compensation even after the section chief, who mainly contacted him to provide payoffs, left Nikko and became a board member at another company, the sources said.

Koike, who is under arrest, also allegedly received illicit payoffs from Nomura Securities Co., Yamaichi Securities Co. and Daiwa Securities Co. as well as Dai-Ichi Kangyo Bank. Sokaiya extort money from companies by threatening to cause trouble at shareholders' meetings.