Brussels (Reuters) - Europe's food safety chief will soon suggest allowing "very limited" amounts of genetically modified material not yet permitted in EU markets to be mixed in imports of foods like maize, rice and soya, she said on Monday.

Her proposal comes as one of the results of a tortuous debate held last month at the highest levels of the European Commission -- the EU executive -- on how to move forward on GMO policy and end years of deadlock between EU countries.

That may change later this year, as EU Health Commissioner Androulla Vassiliou prepares a legal proposal that, provided EU farm ministers agree, would set a ceiling for the amount of unauthorised GM material which could be tolerated in imports.

"The problem is zero tolerance," Vassiliou told Reuters in an interview. "We are not talking about big numbers, we are talking about very limited (amounts) which are already difficult to detect because they are so limited."

That ceiling would certainly be less than 1.0 percent, she said, adding that the proposal should be issued by early August.

At present, EU law sets a tolerance threshold of 0.9 percent for GM material in food and feed, above which a cargo must be labelled as being biotech.

EU feedmakers have long complained of problems sourcing raw material, warning that the consequences of Europe's extreme caution and "zero tolerance" of unauthorised GMOs, even in tiny amounts, could be catastrophic for the food and feed sectors.

The problem for GM crop-growing countries, in particular the United States, Canada and Argentina, is that EU law at the moment does not tolerate the accidental presence of unauthorised GMOs that have been approved elsewhere.

That has led to cargoes of rice and grain arriving at EU ports being impounded by local authorities if sampling shows the presence of unauthorised GM material, disrupting trade flows.

TEMPORARY SOLUTION

Europe has long been criticised by major GMO producers like the United States for its reluctance to embrace biotech foods.

No new GMOs have been approved for growing in EU countries since 1998, in large part because of huge public resistance to what are sometimes called "Frankenstein foods."

Commission experts say the EU takes a minimum of 2.5 years, and often longer, to complete new GMO approvals compared with an average of 15 months in the United States, causing a time-lag in equivalent GMO approvals.

"It (threshold proposal) will not be a permanent solution, just a temporary solution to the problem," Vassiliou said.

"It's not a deviation from our basic legislation which is in order to authorise a GMO, we have to be absolutely sure of the safety of the product," she said.

EU livestock producers do depend heavily on imported soy products -- beans, meal -- as a source of protein-rich and high-quality feed. Nearly all of it comes from Argentina, Brazil and the United States, the world's top three soybean producers.

Since these countries mainly grow GM varieties, non-biotech soy is becoming increasingly difficult to source, they say.