I last saw CBS producer Natalie Liu on last Thursday week at a press preview of the opera Turandot in the Forbidden City. She said she was leaving China shortly after a year working in Beijing and we made tentative plans for a farewell drink.

A striking and vivacious 32-year-old, Natalie Liu was trying to make a name for herself with the American network. I remember also running into her in Shanghai in June during President Clinton's visit when she told me with some excitement that she had got a scoop in Beijing the previous day - an interview with a disgraced communist official called Bao Tong.

When I rang her mobile number on Thursday this week a recorded voice said in English and Chinese: "Sorry, the subscriber is cut off."

Actually, the subscriber was in jail. On Wednesday, up to 14 Chinese security police had raided Natalie Liu's apartment. They searched it for two hours and seized her video tapes, photographs, cassette tapes, name cards and notebooks.

She apparently managed to convey this information to her husband Zhai Haiqing (41) in Bethesda Maryland, near Washington, where he works as a businessman. She did so by locking herself in the bathroom and calling him on her mobile phone.

Then she was handcuffed and led off and her two children aged three and five put in the care of their grandmother. The police allegedly produced no search warrant or statement of charges.

One can only guess why the Chinese authorities did this on the eve of Mary Robinson's much-anticipated first visit to China as United Nations Human Rights Commissioner from September 6th to 15th. Almost certainly it had to do with Ms Liu's travel plans. She had booked a ticket to the United States for Monday to rejoin her husband and the security police usually make their move as someone out of favour is about to leave.

The interview with Mr Bao may have been part of the problem. Foreign news organisations had been warned off from talking to Mr Bao, who spent seven years in jail for encouraging the pro-democracy protests in 1989 and who continues to advocate democracy.

Also Ms Liu, a Chinese passport-holder with permanent resident rights in the US who had left China in 1989 and studied journalism in New York, had been working as a freelance journalist at a foreign bureau, which Chinese citizens are not allowed to do. She was also not accredited as a journalist with the Foreign Ministry.

There may be other reasons that we do not know. The incident certainly sends a message to aspiring Chinese journalists, and raises questions about the responsibilities of western news agencies in hiring them. But nothing could be more sure to serve notice to Mrs Robinson, who arrives in Beijing tomorrow, that China has a long way to go regarding the right to a free flow of information.

She is being pressed by international media groups to raise the case, though individual detentions are unlikely to dominate Mrs Robinson's agenda. She is almost certainly focused on fact-finding, dialogue and signs of progress on a broad front.

Much has been made of the dialogue which has replaced confrontation this year - for the first time since the 1989 Tiananmen crackdown - in the exchanges on human rights between China and the rest of the world. President Clinton was allowed to speak openly on Chinese television about the importance of human rights and religious and economic freedoms when he visited Beijing in June, and US officials afterwards said they hoped the beginning of dialogue heralded a trend toward more political freedom in the communist country.

The Chinese have also built up a portfolio of human rights achievements - village democracy, improved education and living standards, new laws and better training for the judiciary - as proof that they are serious about human rights, and they will impress upon Mrs Robinson the importance of their "Asian values".

A senior Beijing human rights official, Wu Jianmin, laid these out at a UN seminar in August, saying that countries should jointly promote the international human rights cause through "strengthening dialogue and co-operation". He cautioned that while civil and political rights were important, economic, social, cultural and development rights had been neglected. (Since 1992, he pointed out, the Commission on Human Rights has adopted 614 resolutions, of which only 40 involve such rights).

But the western world has a particularly awkward habit for the Chinese of focusing not on high-sounding resolutions but on individual detentions, such as that of Ms Liu this week, or the labour activist Zhang Shanguang, who was arrested on July 21st after trying to organise laid-off workers.

Human rights critics say little has changed. Despite the high hopes of the US administration, US Secretary of State Madeleine Albright found herself complaining to China on July 27th, just four weeks after Mr Clinton's visit, that human rights were going in "the wrong direction" from the one Washington expected.

During a meeting with Chinese Foreign Minister Tang Jiaxuan, she pointed out that more than 20 Chinese dissidents had been detained since the summit. At the same time all 13 dissidents who were detained at the time of the Clinton visit for trying to set up an opposition party have since been released, the last just days ago.

The Australian Foreign Minister, Alexander Downer, said on the other hand last month after two days of dialogue that China's human rights position had improved in the past 14 months, "even if it hasn't been everything that any of us would like". Mr Tang reassured Mrs Albright that China would follow up by signing the UN Covenant on Civil and Political Rights.

This treaty is intended to provide basic guarantees of civil liberties, including the rights of free speech, assembly and association (most of which is already in the Chinese constitution). The Chinese government has been flagging its intentions to sign the covenant for some time. President Jiang Zemin told Mr Clinton that it would do so in the autumn, and many observers here believe that - September being autumn - they have kept it for hand-delivery to Mrs Robinson.

Such an event, coinciding with a meeting between Mrs Robinson and President Jiang at the end of her trip, would dominate news coverage and turn the focus on to China's progress on human rights rather than on its much-criticised past record, or indeed on any criticisms that the UN Commissioner might have of current practices on forced abortion, sales of body organs, labour camps, the death penalty or Tibet.

Mrs Robinson has already applauded China's promises to sign the covenant as a "renewed commitment" to implement "international human rights standards". Such international recognition of progress is allimportant for China's foreign policy goal of taking its place in the world as a respected regional power.

The invitation to Mrs Robinson was part of its strategy, as its timing would indicate. It came not long before the annual UN Commission meeting in Geneva in March when the EU and the United States were looking for justification for a U-turn on China, i.e. abandoning confrontation for dialogue.

This had become inevitable when the EU split the previous year and France, Germany, Italy and Spain, all fast developing their trade with China, refused to support the annual motion criticising Beijing's conduct, citing China's new willingness to enter into dialogue on human rights.

It helped enormously for European countries like Britain - a persistent critic - to be able to use the fact that China had extended an invitation to Mrs Robinson when they sought to justify to their human rights constituencies the decision to opt for dialogue when not much had changed on the ground. Indeed British Foreign Secretary Mr Robin Cook gleefully leaked the information about the invitation to reporters in Beijing as London prepared for its about-face.

Dialogue brought immediate and tangible benefits to western countries, creating a better climate for international co-operation and trade. The very day after the EU dropped its criticism of China, the Minister for Foreign Affairs, Mr Andrews, was warmly embraced in Beijing and congratulated by the chairman of the National People's Congress, Li Peng.

The previous year, when Ireland went the other way, the top Chinese official, Zhu Rongji, cancelled a trip to Ireland in protest. The buck was thereby passed to Mrs Robinson to carry the human rights torch to China.

She will be looked to by human rights groups to say it as it is - Amnesty International for example maintains little has changed on the ground - but at the same time she will not want to come into open conflict with the government of the world's most populous nation.

The EU and the US have created a tightrope for her to walk on. It will require all her skills to navigate it successfully.