UNITED States officials are considering dropping import bans on products from a Chinese farm and factory in an apparent bid to win greater access to China's prison system. It is understood US customs officials have gathered satisfactory evidence to allow them to consider dropping the ''detention orders'' against socks made in Beijing Number One Knitting Factory, and grapes from Qinghe Farm, near the Chinese capital. If the bans are lifted, it will be the first time any of the 24 separate detention orders on alleged forced labour camp products have been lifted since they were first issued two years ago. US officials are believed to hope the goodwill gesture will pave the way for wider inspections of many factories and camps to which Chinese authorities have been denying access. President Bill Clinton has made China's full implementation of the two countries' Memorandum of Understanding on inspection of labour reform institutions a condition for renewing the Most Favoured Nation (MFN) trading status next year. So far this year, US inspectors have been frustrated by the lack of access to sites. US Customs Commissioner George Weise testified before Congress in the autumn that China had barred access to all but one of a list of five sites requested by his officials. However, they have recently been able to visit the Beijing factory and Qinghe farm - even though these were not among the sites requested by the US. It is not known whether they were allowed to view the entire premises, or what conditions were found. US Customs stationed two full-time officials in Beijing this year to try to push the inspection programme forward. The detention order was slapped on the Beijing factory after Congressman Frank Wolf came back from a visit to China in 1991 claiming to have evidence the socks were being forcibly produced, and were available for import into the US. The Qinghe farm was among those sites visited the same year by former laogai prisoner Harry Wu Hongda, when he went undercover with a camera crew from CBS and secretly filmed evidence of forced labour in several factories. Mr Wu has criticised US officials for failing to gain access to the vast majority of the 1,000 forced labour sites he calculates are operating on the mainland. In an interview today in the Sunday Morning Post Magazine, Mr Wu reveals he is targeting Hong Kong for action in his latest campaign, and is planning to publish a ''hit list'' of local firms that either sell or help export prison goods to the rest of theworld. In Washington, an official from the Customs' investigations section would not comment on possible plans to drop the orders, but said if there were cases where there was enough evidence to show the goods were not being produced under forced labour conditions, then those cases could be closed. Assistant Secretary of State for Human Rights, John Shattuck, said on Friday that Beijing had ''shown a willingness to further open its prisons to visitation by US Customs''. Mike Jendrzejcyk of the Washington office of human rights group Asia Watch said it appeared the US was trying to create the impression China was doing enough on human rights so it could ''sell MFN on Capitol Hill''. China admits to a large scale labour reform programme, but denies it exports prison labour goods. Meanwhile, Asia Watch yesterday protested at the treatment of Liu Gang, a veteran of the Tiananmen Square protests who is being held at the Lingyuan Number 2 Labour reform detachment. Liu is in ill-health and has been denied visits by his relatives, who were first turned away from the prison on November 11 and had been refused entry since. Asia Watch and Human Rights in China claim Liu has been tortured and kept in solitary confinement. ''The denial of family visits for Liu Gang removes his only contact with the outside world and puts him at great risk,'' said Sydney Jones, Asia Watch executive director. ''It violates both international human rights norms and China's own stated standards of prisoner treatment. ''This arbitrary action makes us gravely concerned for his well-being.'' Liu was arrested in June 1989 and sentenced to six years in jail in February 1991. The authorities recently released pictures of the prisoner purporting to show him in good health.