As Panama and Costa Rica have both allowed the planting of GM (Genetically Modified) corn, the debate on the safety of GM is heating up in the EU.
A virus gene that could be poisonous to humans has been missed when GM food crops have been assessed for safety.
GM crops such as corn and soya, which are being grown around the world for both human and farm animal consumption, include the gene.
A new study by the EU's official food watchdog, the European Food Safety Authority(EFSA), has revealed that the international approval process for GM crops failed to identify the gene.
As a result, watchdogs have not investigated its impact on human health and the plants themselves when assessing whether they were safe.
The findings are particularly powerful because the work was carried out by independent experts, rather than GM critics.
It was led by Nancy Podevin, who was employed by EFSA, and Patrick du Jardin, of the Plant Biology Unit at the University of Liege in Belgium.
They discovered that 54 of the 86 GM plants approved for commercial growing and food in the US, including corn and soya, contain the viral gene, which is known as 'Gene VI'.