After decades of pushing nations to surrender more power to the European Union, the bloc is pulling back on efforts to assert its authority over one highly contentious issue, genetically modified foods.
On Tuesday, the European Commission will formally propose giving back to national and local governments the freedom to decide whether to grow such crops.
The new policy is aimed at overcoming a stalemate that has severely curtailed the market for biotech seeds in Europe. Only two crops, produced by the agricultural giant Monsanto and the chemical company BASF , are sold for cultivation in Europe.
The new flexibility is aimed at opening up markets in countries like the Netherlands, where governments are favorable toward growing and trading biotech products, while countries like Austria, where the products are unpopular, can maintain a ban.
But far from celebrating the new approach, the growing global industry as well as some farmers themselves are extremely wary.
“So many different authorities suddenly doing so many different things risks sending a message to successful growers in Africa and Asia that authorities are unsure how to deal with biotech,” said Nathalie Moll, the secretary general of EuropaBio, an industry group.
She said it also remained to be seen whether the proposals would conform with World Trade Organization rules.
The United States and the European Union are still resolving a dispute over genetically modified organisms, or G.M.O.’s, and related issues after the trade organization in 2006 ruled against Europe’s de facto ban. Washington could still retaliate in that case.
The Office of the United States Trade Representative declined to comment on the new approach but said it would be on the agenda at a meeting with European officials this month.
Despite “some progress” in recent months, the United States “still has a number of concerns,” said Nefeterius Akeli McPherson, a spokeswoman for the trade representative. They include “a substantial backlog of pending biotech applications, and bans adopted by individual E.U. member states on biotech products approved at the E.U. level.”
The reality remains that the European Union still produces few genetically modified crops, which many Europeans derisively call Frankenfoods.
The United States, Brazil, Argentina, India and Canada are the top five producers of such crops as measured by land under cultivation. The European Union, with 27 member nations, ranks well behind at 14th.
A critical factor behind the proposed change in Europe is a growing frustration with the current system, under which meetings between government officials and ministers often end in deadlock. That forces unelected officials at the European Commission to make the final decision on authorizing biotech products.
The commission has found itself repeatedly pressured on one side by the United States and the W.T.O. to follow the recommendations of its own scientific authorities and enforce the use of approved products and on the other by countries like Austria and environmental groups that believe the European Union authorities are too eager to promote newfangled technologies.
Under the new proposals, the commission would continue to make the approvals itself but leave it to members and local and regional authorities to decide what they want to grow at home.
But whether the new rules will win the necessary approval from European Union governments and the European Parliament still is unclear.
In an unlikely alliance, the Austrian and Dutch governments first made the proposal back in 2008.
The Dutch were eager to ease tensions over biotech crops with the United States and other trading partners, and to ensure continuing imports of animal feeds that contain biotech products.
Animal farming is a big part of the economy in the Netherlands, which, in turn, is a major exporter of meat and dairy products. The Dutch are also involved in developing biotech products.
The Austrians supported the changes as a way to keep its national ban on growing any such crops without facing regular challenges from the European Union authorities.
Other countries, though, have expressed concern about setting a precedent that could undermine European integration. The crisis this year over how to supervise the finances of the 16 nations that use the euro already has highlighted the limits to European cooperation.
“If the agricultural policy is common, why wouldn’t the policy of cultivation of G.M.O.’s be?” asked Elena Espinosa, the Spanish environment minister. Spain grew 80 percent of the biotech corn, intended to resist a pest called the corn borer, produced in Europe last year.
In addition, Belgium, which has just taken over the rotating European Union presidency, is concerned that a ban by a single country could put the entire bloc in danger of facing retaliatory trade sanctions.
Even farmers that favor biotech crops are concerned that the commission is offloading a problem on them — and that the issue could become even more politicized than it is now.
“The Welsh and the Scots are vehemently opposed to genetically modified crops,” said Philip Lodge, who would like to farm biotech sugar beets in Yorkshire, in northern England. “With these conflicts of interest so close to home, I just don’t see how I’ll be able to grow G.M. in practice.”
Other farmers warned that the change risked stirring up new confrontations with activists, who in the past have destroyed crops planted in trial fields.
“The prospect terrorizes me,” said Jerome Hue, who farms in Carcans, France. “If every locality can ban G.M.O.’s, I don’t see how we will be allowed to grow the crops anywhere in France anymore.”
Mr. Hue grew corn produced by Monsanto before the French government imposed a national ban in 2008. France has said it would consider lifting that ban once the European authorities have assessed new evidence about the effects of modified crops on the environment.
Mr. Hue said biotech opponents could erect beehives at the edges of farmers’ fields to pressure the authorities to impose new bans if the honey picked up traces of the modified genes.
But commission officials and some other member states like the Netherlands say the new policy points the way to managing an increasingly unwieldy group of 27 countries.
Last week, in the latest example of the persistent differences, countries failed for a third time to break a deadlock over whether to allow imports of six varieties of bioengineered corn for food and feed made by Monsanto, Dow AgroSciences, Pioneer Hi-Bred and Syngenta.
That leaves the decision up to the European Union’s health commissioner, John Dalli, who is expected to approve the products in coming months. He caused a furor among environmentalists in March when he approved cultivation of a biotech potato by BASF — the first such approval in more than a decade in Europe.
In the European Parliament, among those reviewing the proposed new rules will be José Bové, a French sheep farmer who captured worldwide attention a decade ago for ransacking a McDonald’s restaurant to protest the influence of multinational corporations. Since then he has served time in a French prison for damaging biotech crops.
He is now a deputy chairman of the agriculture committee at the European Parliament, where he was elected as a member of the Green Party.