FORMER prisoner and veteran campaigner Harry Wu Hongda has become the latest pawn in the US-Sino political dispute. American consular officials were on their way to the city of Horgas, where Mr Wu was detained as he tried to cross into China from Kazakhstan last week, US State Department spokesman Christine Shelly said. Mr Wu, head of the California-based Laogai Research Institute and a regular investigator into forced labour camps and the trade in human organs in China, was apparently on another secret mission but was recognised by officials at passport control. China confirmed Mr Wu was under detention but said the activist was being investigated for illegally entering restricted areas during a visit last year. Foreign Ministry spokesman Chen Jian said Mr Wu and his female American travelling companion had been stopped by border authorities as they entered Xinjiang on June 19. Mr Chen, citing information from public security authorities, identified the second individual as Haowei'er Su - a Chinese transliteration of the name Sue Howell. He denied that the pair had been 'arrested', saying the authorities had questioned their entry documents and visas and made investigations. 'The investigation into Haowei'er Su is over,' Mr Chen said. Ms Howell was expelled from China and is now back in the US, but Mr Wu was being lodged in a hotel in the oil-town of Karamay, at the expense of the local authorities. It was not clear why the information contradicted that of the US State Department and if the authorities had moved Mr Wu to Karamay. Checks were still being carried out on the activist in relation to a trip to China from April 1 to May 6, 1994, Mr Chen said. 'Without the approval of the relevant supervising authorities of China, Mr Wu Hongda repeatedly entered restricted or non-open areas and organisations of China, thus violating the laws of the People's Republic of China on the entry and exit of aliens,' he said. During his trip last year, Mr Wu, 58, worked with a British television crew, secretly videotaping sales of human organs. Republican Congressman Chris Smith, who has invited Mr Wu to testify on prison labour before a House sub-committee, was last night 'very upset' over his detention, said an aide, and would press the Chinese Embassy in Washington for Mr Wu's immediate release. However, Mr Wu's colleague at the Laogai Institute in Washington, Jeff Fiedler, said he feared Mr Wu had become caught in the middle of a political dispute. 'There's no doubt that the Chinese have known who he is since last week,' said Mr Fiedler. 'This is all political. But I don't think it's in their interests to make him into a martyr.' 'It is serious if they are trying to pin [his alleged offences] last year on him,' said Mr Fiedler. 'My view is that the revelations on forced labour burned them, but the organ stuff sent them into orbit.' Mr Wu's wife, with whom he has entered China on undercover investigations, yesterday flew from California to talk to authorities in Washington.