MANUFACTURERS, the Government and trade analysts have condemned the European Union (EU) for levying anti-dumping charges on 3.5-inch computer diskettes. They have described the practice as ''illogical and unfair'' and also claim the EU has ''cooked up'' the move because its own producers have been losing sales. And they fear the punitive action will discourage Hong Kong's export sales. On Wednesday, the European Commission in Brussels levied duties of up to 35.7 per cent on all imports of 3.5-inch diskettes from Hong Kong and South Korea, back dated to February 12. It followed last September's complaint by the EU which said Hong Kong and South Korean companies' prices ''substantially undercut'' those charged by EU producers, forcing the Europeans to align their prices with the imports. Hong Kong companies specifically cited as having co-operated with the EU's investigation were: Swire Magnetics, Technosource Industrial, Plantron (HK) Ltd and HK Jacklin Magnetic Company. Histoshi Yoshimura, sales manager for Technosource Industrial, said the company would explain to the EU its prices did not constitute dumping. ''We want to sell at a much higher price but European customers ask for the lowest prices. I think some European disk manufacturers face pricing problems. We sell by the market price,'' he said. A spokesman for Swire Magnetics said the company had stopped manufacturing diskettes in late 1993 because the product ''was not commercially viable'' and the market too competitive. Neither Plantron nor HK Jacklin could be reached for comment. Dr Leonard Cheng, associate dean of the School of Business and Management at Hong Kong University of Science and Technology, said the EU's action was symptomatic of the lack of competitiveness of European manufacturers. He said the EU was effectively admitting European manufacturers were not increasing their sales because Hong Kong firms were charging lower prices. He added many anti-dumping cases, especially those originating from the United States, were based on complaints that had been ''cooked up''. ''Sometimes a price is stated in terms of seasonal variations. Depending on what price you pay, the exporter could be accused of dumping if he did not set the same price for the whole year,'' he said. Maria Kwan, assistant director-general of trade, called the measure ''trade harassment'' which could discourage export sales. ''Importers will wonder about their bottom line. They won't know about [the amount of duties to be charged] at the end of the day when the products will be delivered.'' Ms Kwan was particularly critical of the high 35.7 per cent anti-dumping duties the EU will exact from all Hong Kong diskette exporters. She called it ''prohibitively high'' and said it would harm investment. ''At least one company has hinted they may stop exporting,'' she said. The four Hong Kong companies, which have submitted replies to the European Commission's inquiries, will have their exports to the EU penalised at varying rates of duty.