The US and Brazil have had their share of trade disputes, yet the latest incident may be the first where accusations of spying have been bandied about.

Brazil said an official of the US Department of Agriculture (USDA) was spotted in a soya-bean field in the interior of Bahia state, apparently investigating a dangerous fungus that causes the crop to lose its leaves and seriously affects production.?They are practising bio-terrorism,? charged one Brazilian agriculture official, suggesting the USDA official was trying to spread the fungus.

Whatever he was doing in Bahia, the USDA agent, who was officially in Brazil to attend a conference on phytopathology (plant diseases), was asked to leave the country. Brazilian authorities say he had not informed them of his botanical field trip. US officials confirmed the incident but were still investigating what the USDA agent was actually doing in Bahia.

Over-reaction or not, Brazil is vying with the US to become the world?s leading soya-bean exporter ? and all?s fair in love and war.