Livedoor Co. founder Takafumi Horie, who stepped down as the Internet firm's president Tuesday, resigned from the boards of all Livedoor group firms Wednesday, the company said.

Fumito Okamoto, who resigned Tuesday as president of Livedoor Marketing Co., left the parent company's board along with Horie, now that both have been arrested, the company said. Okamoto also resigned from the board of mail order firm Cecile Co.

Livedoor said Tuesday it could not confirm if Horie, 33, intended to step down from the board when he said he would leave the presidency.

Horie, Okamoto and two other group executives -- former Chief Financial Officer Ryoji Miyauchi and operating officer Osanari Nakamura -- were arrested Monday on suspicion of violating the Securities and Exchange Law.

Prosecutors got the four suspects' detention without charge extended by 10 days by the Tokyo District Court on Wednesday to give them more time to decide whether to indict the men over allegations the Livedoor group mislead financial markets over one of its subsidiaries' acquisition deals in 2004. When the extension ends on Feb. 3 they can file for another 10-day extention.

Horie and the others allegedly conspired to spread false information to investors in order to boost the subsidiary's share price. Prosecutors also suspect the group was involved in accounting fraud in 2004.