One dissident was detained in one of the cities which Mr Clinton will visit; three of the travelling American journalists had their Chinese visas withdrawn; and the Chinese Communist Party chief who was deposed during the June 1989 Tiananmen Square crackdown called on the party to admit that the massacre was "one of the biggest human rights problems this century".
Human rights issues may yet overwhelm the nine-day visit to the mainland and Hong Kong and represent the biggest political risk both to Mr Clinton and his Chinese host, President Jiang Zemin.
Unexpected controversy could yet derail a summit which is supposed to set the seal on a more stable Sino-American relationship and seek progress on subjects ranging from weapons non-proliferation and trade tariffs to the environment.
Yesterday's surprise came in the form of a letter to the party Central Committee from Zhao Ziyang, the reformist general secretary of the party who has been under house arrest since the massacre on 4 June 1989.
He appealed to China's leaders to re-assess the terrible events of nine years ago. "President Clinton's visit to China marks a turn for the better in Sino-US relations. But the United States and the whole of the West have again and again raised the 4 June problem and the human rights problem of China," he wrote. "Rather than let it become an obstacle to international relations, it would be better to resolve the 4 June problem ourselves voluntarily," he said, though the suggestion will appal China's present leaders.
The letter was seen by the Reuters news agency. There was no way to confirm independently whether it was genuine. But the report will increase the pressure on Mr Clinton to make a forthright statement on the legacy of June 1989 on his visit.
Across China, the country's remnant dissidents are under close watch. In the city of Guilin, police officers took Li Xiaolong, 34, a member of the now-defunct dissident group Human Rights Voice, into custody.
China also withdrew visas from three American journalists on the press plane with Mr Clinton to China. The reporters work for Radio Free Asia, a US government-funded broadcaster which beams its robust anti-Communist coverage of the mainland back into China.
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