Sao Paulo, July 5 (OsterDowJones) - Soybean exporters from Brazil, theU.S. and Argentina are demanding their respective governments pressureChina to stop arbitrarily restricting imports of their world-leadingoutput.Six groups representing soybean exporters sent joint letters to U.S.President George Bush, Argentine President Nestor Kirchner and BrazilianPresident Luiz Inacio Lula da Silva asking them to force China intochanging its policy of restricting trade by canceling contracts, banningindividual companies and imposing arbitrary and onerous trade rules, thusbreaking World Trade Organization agreements.Brazilian exporters are spearheading the initiative after Chinatemporarily banned local soybean imports from 23 companies in May and Juneafter finding extremely low levels of fungicide in a number of shipments.The ban has been lifted but exporters lost a lot of business and are stillawaiting payment on shipments sent."Unfortunately, these aren't the first cases in which they have triedto administrate the flux of trade through non-tariff barriers, which isprohibited by the World trade Organization," read the letter, seen byOsterDowJones.Both U.S. and Argentine exporters have previously been affected byChina's lack of transparency as the Asian giant routinely delays andcancels issuing of import permits.China is the world's main importer of soybeans. The U.S. Department ofAgriculture forecasts imports will reach 24 million tons in the year fromSept. 1.The letter specifically demanded that governments pressure China torescind new sanitary import rules, introduced July 1, which are much morestringent than international standards.It went to ask that the government obtain assurances that China willcease to use administrative restrictions to limit trade. If it shouldcontinue to do so, the government should consider lodging a complaint atthe World Trade Organization, it added.The letter was sent by Brazil's National Cereal Exporters Associationand the Brazilian Vegetable Oil Processors Association, by Argentina's OilIndustry Chamber and the Cereal Exporters Center, and the North AmericanExport Grain Association and the National Oilseed Processors Association.