Now, experts at the Commission's Joint research Centre (JRC) have issued a report on how much GMO content can be reasonably allowed in crops like maize and rapeseed before the seeds have to be labelled as biotech.

Batches of conventional seed containing genetically modified material below those thresholds would not have to be labelled.

While a threshold of 0.5 percent would present few, if any, problems for maize, cotton and sugar beet, to lower it to 0.3 percent would require extra measures like arranging seed plots on farms to take dominant wind patterns into account, it said.

"The production of seed up to 0.5 percent GM content would be possible with little or no change in current seed production practice," the Commission said in a statement on Friday.

With a 0.5 percent GMO threshold in seeds, it would still be possible to grow crops that did not exceed the EU's 0.9 percent threshold for food and animal feed. Any GMO content above this level requires that food and feed must be labelled as biotech.

DEADLOCK

A new law on seeds would replace current legislation dating from 1998, and is widely seen as the piece that will complete the European Union's jigsaw of GMO laws.

In 2004, the EU executive broke up in deadlock over the last draft version of a seeds law that called for 0.3 percent GMO thresholds for maize and rapeseed. The draft before that listed six crops with proposed thresholds between 0.3 and 0.5 percent.

Nothing much has happened on GMO seed thresholds since then.

Green groups say seed thresholds should not exceed a 0.1 percent technical detection level, since anything higher makes it impossible to meet strong consumer demand for non-GMO food: a view backed by GMO-sceptic countries Austria and Luxembourg.

The Commission report said to achieve such a low level would be impossible if countries did not extensively apply rules for separating traditional, organic and GMO crops -- a concept known as co-existence in EU jargon.

"Guaranteeing that maize seeds will contain no more than 0.1 percent adventitious (accidental) GM presence is not possible if co-existence measures are limited to action on individual farms or coordination between neighbouring farms," the statement said.

Green groups criticised the JRC's report, saying it assumed that a 0.9 percent threshold was a "target" for GMO presence rather than a maximum permitted content. Another study should be carried out on keeping foods and crops GMO-free, they said.

"The approach that the JRC has chosen in its report is completely flawed and will lead to massive genetic contamination of the European countryside," said Geert Ritsema, GMO campaigner at Greenpeace International.

"This report is biased towards the interest of the biotech industry and goes against the will of the vast majority of European consumers who do not want to eat GMO’s," he said.