Tsugio Yukihira, chairman of Yamaichi Securities Co., officially stepped down August 6 as head of the Securities Dealers Association of Japan to take responsibility for alleged illegal payoffs to a "sokaiya" corporate extortionist.

Seiichi Kato, chairman of Okasan Securities Co., was appointed acting chairman of the industry association. Kato will hold the position "for the time being" until a new chairman is appointed, he told reporters. Kato said he has no intention of assuming the chairmanship.

The personnel decision was made at a meeting of the association's vice chairmen held earlier in the day. The association had six vice chairmen including Kato.

Kato admitted at a news conference that Okasan had in the past engaged in transactions with Ryuichi Koike, who owned shares of the brokerage house, but said that no illegal deals were involved. He firmly denied any problematic dealings between his firm and racketeers.

Kato also denied personally knowing any sokaiya although he served as Okasan's president for 36 years until June this year. Okasan is a second-tier brokerage house.

Yukihira was appointed as industry head on July 1. His predecessor was Nomura Securities Chairman Masashi Suzuki, who resigned in March following revelations of his brokerage's illegal payoffs to Koike.