A passenger filmed on a bus allegedly used by Taiwan's main opposition Kuomintang to take people to a pre-election rally in Kaohsiung has admitted to prosecutors he was asked by 'one of the mayoral candidates' to buy votes for NT$500 (HK$120). Prosecutors said yesterday that the man, nicknamed 'Black Pine' and surnamed Tsai, had told them that one of the mayoral candidates was publicly buying votes. The passenger also said he had been asked to distribute the money by the man who rented the tour bus, surnamed Ku. 'One of the mayoral candidates publicly bought votes, so that person's criminal intention is very obvious,' prosecutor's office spokesman Chung Chung-hsiao said, without identifying which candidate. The authorities are still trying to find Ku. Prosecutors have applied to detain Tsai and were still interrogating him yesterday. Huang Chun-ying, the KMT mayoral candidate who lost to Democratic Progressive Party opponent Chen Chu, was accused by the DPP of buying support by paying people to participate in a pre-election rally. The KMT's alleged wrongdoing was videotaped by a person Ms Chen described as one of her volunteers. The accusation drew strong protests from the KMT and Mr Huang has filed a countersuit against Ms Chen for libel and malicious intent in seeking to deprive him of victory. Kuomintang chairman Ma Ying-jeou said yesterday the tour bus did not belong to his party and that the video was part of a DPP plot designed to discredit the KMT. 'This has not only violated the law, the issue is also politically immoral,' Mr Ma said. 'We want them to apologise to us.' Ms Chen, a 56-year-old former labour chief, beat Mr Huang, 65, by the thin margin of 1,114 votes in an outcome that helped consolidate the ruling party's hold of Kaohsiung. The scandal ahead of the election hurt the KMT's chances in the island's main southern city.