The United States will have to wait until next year to see its fight with the European Union over biotech foods resolved, as the World Trade Organization agreed to an E.U. request to bring scientists into the debate, officials said Thursday.

A WTO panel in Geneva decided Aug. 20 to allow expert testimony before deciding on the complaint filed last year by the United States, Canada and Argentina over the E.U.'s moratorium on approving genetically modified foods for sale in Europe.

That means the panel's report, initially expected before the end of this year, now will be delayed until late March, according to WTO documents.

The United States argued that scientific advice was not needed because the case revolved around legal issues, while the E.U. sought to move the debate from trade rules to health and environmental protection.

A U.S. official said the government accepted the panel's decision and would help frame the questions to be debated. There was no immediate E.U. comment.

The E.U. ended its six-year moratorium in May when it allowed onto the market a modified strain of sweet corn, grown mainly in the United States.

Another herbicide-resistant corn was approved for animal feed last month. In both cases, the decision was made by the E.U.'s executive commission after ministers from the 25 member governments deadlocked on the applications.

The political stalemate highlights continuing unease in Europe over biotech foods, despite the introduction last spring of what are considered the world's most stringent labeling requirements.

The United States has said it will continue with its WTO case until it sees a "predictable, ongoing process" based on science, not politics. It also opposes the E.U.'s strict labeling, saying it unnecessarily scares away consumers.

Biotech crops have been widely grown in the United States for years, including corn and soybeans genetically modified to resist insects or disease. U.S. farm exporters contend the ban has stopped about $300 million in annual sales of bioengineered corn to Europe.

U.S. officials have expressed concerns that Europe's anti-biotech sentiment is spreading to developing countries, exacerbating global hunger.

WTO spokesman Peter Ungphakorn in Geneva said it was not unusual for the trade organization to seek scientific advice. Scientists have been called in to assist panels dealing with disputes over asbestos and animal- and plant-health issues.

An anti-biotech group, Friends of the Earth Europe, called the WTO panel's decision a first-round victory for the E.U. but attacked the "secretive and undemocratic" WTO for getting involved at all.

"Every country should have the right to put public safety before the economic might of the biotechnology industry," said Adrian Bebb, a spokesman for the group.

Associated Press correspondent Jonathan Fowler contributed to this report from Geneva.