The arrest of Livedoor Co. founder Takafumi Horie has rocked the ruling Liberal Democratic Party, which had unofficially supported the 33-year-old Internet tycoon in the Sept. 11 general election as a standard-bearer in Prime Minister Junichiro Koizumi's reform drive.

On Tuesday, LDP Secretary General Tsutomu Takebe expressed regret for having supported Horie. "The party didn't authorize or recommend (Horie as a candidate), but I personally must humbly (express my) regret," Takebe told a news conference in the morning.

Takebe insisted he supported Horie in the 2005 election "on my own judgment, without consulting with Prime Minister Koizumi."