* 150,000 T maize unloaded in past week
* Wheat stocks now 300,000 T
* Wheat sales in port slow, maize in demand
* Barley exported
(Adds industry comment, paragraph 3 and 4)
By Martin Roberts
MADRID, Oct 22 (Reuters) - The Spanish port of Tarragona was unloading 49,500 tonnes of maize from a ship coming from the United States, a port source said on Friday, the first U.S. shipment in years due to concerns about genetically modified grains.
Officials at Spain's leading grain port were not immediately available for comment, but the port roster showed that the Ioannis K had set sail from Myrtle Grove, Louisiana, with a cargo listed as "agri-livestock and food", which includes grain.
Spain has not imported U.S. maize for years because it has consisted of genetically modified strains not approved in Europe, although Brussels did approve six GM maize varieties for import in July.
The move modified the EU's previous zero-tolerance stance, which forced shipments of U.S. soy to be rejected last year after they were found to contain minute traces of unauthorised GM maize.
Jorge Saja, of feed compounders' group CESFAC, said dealers were offering U.S. maize for December delivery, following the expected ratification in November by European Agriculture Ministers of a low level presence (LLP) of GM maize strains.
"If the LLP solution is approved in a few weeks, and given that all maize and soya strains grown in the Americas are at least scientifically approved, the door could be opened for U.S. maize to return," he said.
Spain may import up to 2 million tonnes of maize a year at a special cut levy under the terms of a trade accord originally designed to compensate U.S. farmers for the loss of an important market when the country joined the EU's forerunner in 1986.
For many years, however, the so-called "abatimiento" scheme has been used to import maize, the ingredient of choice for animal feed makers, from other origins.
No bids were tendered at the last auction for cut-levy maize held last week, but that was expected because Brussels has set the maize levy at zero.
WHEAT DEMAND SLOWS
The source added that northeasterly Tarragona had also unloaded 46,000 tonnes of maize from Brazil in recent days, and another 54,000 from Ukraine.
"With grain prices at the levels they are, consuming maize in (animal feed) formulae is more advantageous because it has more protein," he said.
"As for wheat, the domestic market is up and running, and wheat here is very expensive, deliveries are not significant."
Prompt feed wheat was last offered at about 208 euros a tonne in Tarragona, although dealers said it could not compete with domestic new crop from a harvest that was much improved on last year.
Maize was quoted at 215/220 euros/tonne.
Tarragona wheat stocks are close to full capacity at an estimated 300,000 tonnes after a flurry of imports from Romania and Bulgaria in recent weeks, but no new shipments were chartered.
Another product making a reappearance after a lull was sorghum, 44,000 tonnes of which has recently arrived from the United States, although it was not selling well.
And in an unusual move in a country that depends on grain imports, a small cargo of domestic barley was shortly to be sent to Tunisia, adding to recent exports from Valencia, a Mediterranean port closer to grain-growing areas. (Reporting by Martin Roberts; editing by Keiron Henderson and Jane Baird)