But David Ji's daughter asserts he is being held over a dispute State-owned TV giant Sichuan Changhong Electric has denied it is behind the seven-month detention of Chinese-American businessman David Ji Longfen . Mr Ji, president and co-founder of home electronics firm Apex Digital, was taken away by mainland police in Shenzhen on October 24 and transferred on the same day to Mianyang in Sichuan province . Apex has been involved in a dispute with Changhong, which is based in Mianyang, since 2002. His daughter, Jean Ji, firmly believes that he is being held as a bargaining chip over the dispute, citing the close ties between Changhong and the Mianyang government. She warned that the case, which highlights the risks of doing business with companies closely linked with the authorities, would send out negative signals about the mainland's business environment. Jack Auspitz, the lawyer representing Changhong in the United States, denied that the company had anything to do with the detention. 'Changhong is not detaining Ji. And just as Changhong is not detaining Ji, it does not have the power to cause his release,' Mr Auspitz said in reply to questions from the South China Morning Post. 'Changhong has made clear to Apex and to Ji's criminal counsel its willingness to co-operate in any lawful efforts they initiate to secure Ji's release.' Asked to comment on Mr Ji's detention, Mr Auspitz said it was understood that 37 bad cheques formed the basis for the mainland authorities' decision to detain him. Apex began trading with Changhong in 2001, but relations turned sour later and Apex claims that Changhong shipped it shoddy goods. The dispute heightened after Changhong accused Apex of owing it more than US$450 million, including about US$85 million for 37 bad cheques Mr Ji signed in 2003. Changhong has launched a lawsuit in the US against Apex. Mr Auspitz insisted that Changhong was determined to pursue its claims through legal channels. It is not known whether the company has reported the case to the Mianyang or Sichuan police. Changhong's president, Zhao Yong , was once the city's deputy mayor. Ms Ji said her father had signed about 20 agreements in October that basically transferred all Apex assets - and even their Los Angeles home and her parents' two cars - to Changhong, and that three hours after signing them he was sent to a Mianyang detention centre for a month. He was released from the detention centre on November 29 but immediately put under residential surveillance - a kind of house arrest that can last six months - she said. Asked about the whereabouts of Mr Ji, the Mianyang public security department's financial crime investigation team declined to be interviewed, saying the case was under investigation. According to mainland law, Mr Ji either had to be released, charged, or serve a maximum one year of bail [qubao houshen] from May 29, said Andrea Worden, a Washington-based lawyer representing Apex in the American lawsuit. Ms Ji has asked the American media and lawmakers to urge the mainland authorities to free her father. 'They basically kidnapped my father and held him hostage,' she said. She said her father was being used as a bargaining chip. 'Originally I thought it was to be resolved through legal channels. Instead they detained my father as leverage to gain advantage in a business dispute,' she said. Ms Ji added that she had read many one-sided reports in the mainland media describing his father as an 'evil, greedy businessman'. 'Whatever disputes they have, the way they are handling it is terrifying,' Ms Ji said. Through her father's infrequent calls, Ms Ji knows he is subject to round-the-clock surveillance in the city's Fuleshan International Hotel, and that their conversations were taped. The hotel has said no such guest is staying there. She has fears for her father's health as he has high blood pressure. She also worries about the prospects of his getting a fair trial in Mianyang. 'If he is tried locally in Mianyang, where Changhong is a No1 taxpayer or income source, and handled by the same people, I don't think my father will have a fair trial,' she said.