The European Union acted illegally in stopping imports of genetically modified foods, the World Trade Organization has reportedly ruled.
Genetically modified crops have been grown in the US for years
Diplomats have leaked details of the WTO's confidential final verdict, not due for public release until late June.
According to reports, the decision is "substantially" similar to a preliminary verdict issued in February.
The case was instigated by the US, Canada and Argentina who were critical of an EU moratorium on GM food crops.
The trio of nations argued that the ban, in place from 1998 to 2004, was about protectionism rather than science.
It is reported that in the 1,000 page ruling, the WTO also criticises Austria, Belgium, France, Germany Italy and Luxembourg for banning several genetically modified organisms (GMOs) already cleared by the European Commission.
However, the verdict is not thought to address the issue of whether GMOs are safe or if they can be compared to naturally occurring products.
Anti-GMO protesters said that this meant the report would have no impact on EU policy .
"It is clear that the US, Canada and Argentina will not be able to use this ruling to bully other countries to accept GMOs," said Eric Gall, political advisor to environmentalist group Greenpeace in Brussels.
Two years ago the moratorium was lifted and a modified strain of sweet corn, grown mainly in the US, was allowed onto the market.
But Washington continued with the WTO case because it wanted to be sure approvals for GMO sales were being decided on scientific rather than political grounds.
Biotech crops, including corn and soybeans that have been genetically modified to resist insects or disease, have been widely grown in the US for years.