The Brazilian port of Paranagua stepped up its ban on exports of genetically modified soybeans in May, despite a Supreme Court ruling in April that the port must ship the GM beans, the Dow Jones news agency reports.

The port says it doesn't have the facilities to segregate GM and non-GM produce, but the Supreme Court ruled that argument isn't valid.

During the month of May, the port turned back 745 truckloads that tested positive for GM soy. That is equivalent to 7% of the total number of truckloads that were shipped out of the port in May. Between January and April, the port turned back roughly 3% of all soy shipments as a result of the ban.

Between May 28 and June 8, the port turned back nearly 200 truckloads of soy, 80 of which port authorities said were being transported by Adubos Viana for US agrifood company Cargill.

According to a port spokesperson, all of the truckloads had been tested and were certified as GM-free by a third-party prior to entering the port but showed traces of GM soy when retested after entry in the port.

Last week, Brazil's federal audit court ruled that the Transport Ministry must intervene at the port to allow GM soybean exports. The ministry has 90 days to implement the Supreme Court's April ruling.

Brazil is the world's second-largest soybean producer, turning out approximately 51 m tonnes this year after initial expectations had put the crop as high as 65m tonnes.

Some 21% to 26% of Brazil's 2004-05 crop was GM, according to a survey by the local Celeres agricultural consultancy.

Brazil was the last major producer to approve legislation for the use of GM seeds.