SOVIET UNION SEEN WATCHING CHINA GATT APPLICATION China's application to join the General Agreement on Tariffs and Trade (GATT) is seen as a test case by the Soviet Union, which will probably demand to follow China, a top European Community official said. Willy de Clercq, External Relations Commissioner of the European Communities, told a news conference that China's application would involve long and difficult negotiations. China formally applied to join GATT in July 1986 and in February presented a memorandum backing its application, which De Clercq said was now being studied. Questions would then be presented to China. "After China, other important state-trading countries including the Soviet Union, will probably demand accession. China's application could be considered a test case," he said. He said the EC strongly backed China's application, but others among GATT's 92 contracting parties took a tougher line. Among the numerous problems of a huge centrally-run economy entering a free trade system are tariffs and reciprocity and the expectation that China will practice an open-trade policy without trade discrimination, de Clercq added. De Clercq noted the different dimensions of the Chinese economy and those of Hungary and Yugoslavia, the two current Socialist GATT members. On China's import potential, he said a foreign exchange shortage would force China to import less this year and next than in the past, with an emphasis on technological equipment and capital. During his visit, De Clercq has met top Chinese leaders and today signed an agreement to open a European Community Commission office in Peking.