THREE Guangdong activists have been detained for allegedly trying to distribute handbills calling for a faster pace of democracy. Sources in the dissident community said the arrests took place on April 6 at Guangzhou's Baiyun airport as the three, Li Guoheng, Liang Weimin, and Wu Songfa, were about to board a plane for Shanghai. They were carrying a few hundred copies of a ''Letter to the Citizens of Shanghai'', which called for a ''democratic, open society''. It is understood that the three, who are young workers and traders in Shunde, are members of a small and informal group of dissidents based in the Pearl River estuary boom town. Friends of the trio said they were being held at the Shunde Detention Centre, but they had not been charged with any specific offence. Moreover, they were denied visits by their relatives, who were only allowed to send them food and medicine. The relatives expressed fears that the three could be held for a prolonged period without access to judicial processes. The letter to Shanghai citizens said it would not do for Beijing to institute economic reform in the absence of political change because people's expectations for political liberalisation were rising. But it argued that political reform should only be ''gradual and step by step''. For example, the letter said, reform should begin with a parliamentary system, such as the open election of the senior officials of the National People's Congress. ''We should gradually build up a democratic, open society,'' it said. Sources said that Li, 31, was a former teacher who had taken part in the pro-democracy movement in early 1989. They said police had seized letters and other documents from his home and a few members from the same group had fled Shunde. The sources added that small-scale activities to ''spread the message of democracy'' and to commemorate the June 4, 1989 crackdown were being staged in cities including Tianjin and Beijing. Diplomatic analysts in Beijing said that security had been tightened in a number of cities in recent weeks. But they said that this was as much a precaution against popular discontent spurred by hyperinflation as efforts to observe the anniversary. Meanwhile, Washington has welcomed the release on parole of political prisoner Xu Wenli on Wednesday. State Department spokesman Mr Richard Boucher said: ''We welcome the news that Xu Wenli has been released from prison. Xu's case has figured prominently in our own human rights dialogue with the Chinese. ''We will continue to urge China to release all those like Xu detained for peaceful expression of their political or religious views,'' he said.