AVOIDING political activity was one of Wang Juntao's conditions when permission was granted for him to seek medical treatment in the United States. An informed source said yesterday the Justice and Public Security authorities had told the ''black hand'' dissident he must agree to conditions before ''medical parole'' could be granted. Mr Wang, 35, was told he was granted bail only for the purpose of medical treatment overseas and he should not see his parole as an opportunity for other activities. ''He was also informed he could not do anything in the US other than seek medical help and recuperation,'' the source said. He was also told never to forget he is a Chinese citizen, the source said. Sources in the dissident community in China said this meant Mr Wang must not join ''anti-Chinese'' organisations run by overseas dissidents. Moreover, Mr Wang was, in effect, forbidden to speak out against the Communist Party administration. The punishment for straying from these criteria, sources said, would be a permanent ban on his return to China. It is not known, however, whether Mr Wang gave the authorities specific pledges on these conditions before he left China. Since arriving in the US, Mr Wang and his wife, Hou Xiaotian, have indicated their wish to return to China after Mr Wang's recovery from liver and heart ailments. Friends of the couple said Mr Wang would give a press conference in New York tomorrow. Meanwhile, Chinese sources said a number of dissidents had left the large cities or gone into business to avoid being detained by security officers in the sensitive period in the run-up to the fifth anniversary of the June 4 crackdown. Well-known dissidents Zhou Duo and Liu Xiaobo, who in March initialled a petition to the National People's Congress demanding constitutional changes, are apparently avoiding political activity for the time being. Mr Zhou left for the north China port of Tianjin this month and is now doing business there with a cousin. Mr Liu, a former lecturer in literary theory, has gone into the production of television commercials. It is understood that several dissidents from an inland province have recently fled to the southern part of the country to avoid detention. ''As in 1992 and 1993, Beijing will probably take pre-emptive action before the anniversary of the massacre by locking up the 'ringleaders' of the dissident movement,'' a source said. ''Detentions this year are expected to be more extensive due to the large number of dissidents who have openly indicated they will stage protests on the eve of June 4.'' Diplomats in Beijing said more People's Armed Police officers had been deployed in the capital since the ''illegal'' circulation of pro-democracy petitions and other protest actions in March.