BUENOS AIRES (Dow Jones)--Argentina, Brazil and the U.S. will send aletter to Chinese officials next week detailing their concerns about hownew food import rules in China might affect trade, Argentine AgricultureSecretary Miguel Campos said Saturday.The two South American nations combine with the U.S. to sell about 92%of the world's soybean exports, according to the U.S. Department ofAgriculture.China is the world's top soybean importer. The Asian giant is expectedto import 24 million metric tons of soybeans in 2004-05, USDA data show.China's demand for soy has rocked commodities markets in recent years,pushing prices up but also causing values to fluctuate dramatically.This has caused headaches for many soybean exporters. Matters weremade worse last month, when China changed its food import rules, causingfurther concern about how the country will deal with soy imports thisyear.To obviate any problems, Campos, U.S. Agriculture Secretary AnnVeneman and Brazilian Agriculture Minister Roberto Rodrigues will jointlywrite a letter to Chinese officials that expresses concern over the newrules.The decision to send the letter was made Friday after Campos met withRodrigues and Jim Butler, the U.S. Deputy Under Secretary for Farm andForeign Agricultural Services."We made the decision to express our concerns in a letter to AQSIS(China's General Administration of Quality Supervision, Inspection andQuarantine) and to the Ministry of Health," Campos said. "We are going toask for a technical meeting to inquire about the possibility of modifyingthese new rules."The letter will be delivered to Chinese authorities next week byambassadors from the three signatories, an Agriculture Secretariatofficial said Saturday.