European Union agriculture ministers were to hold emergency talks in Luxembourg Tuesday on the bacteria crisis that has left 23 dead, as the source of the outbreak remained elusive.
The European ministers will discuss aid for farmers who are unable to sell their vegetables due to growing consumer fears over the E. coli outbreak, and the sensitive issue could see acrimonious exchanges.
They will also review the bloc's food safety alert system to ensure that warnings have "scientific basis and proof" before becoming public, EU health commissioner John Dalli said.
Dalli said the alert system review was requested by Spain, where farmers were hit hard by inaccurate warnings that the outbreak might be linked to Spanish organic cucumbers.
Madrid has said it will demand full compensation from Germany for the losses which Spain's fruit and vegetables exporters association, FEPEX, estimated at 225 million euros (ê328 million) per week since the crisis began.
"We have told Germany that it must reimburse us for the loss. If it covers 100 percent, which is what we are demanding, the affair will be closed. Otherwise we reserve the right (to take) legal action," Spanish Agriculture Minister Rosa Aguilar said on Monday.
"We are not going to allow our producers to lose one cent, because they are not to blame."
Germany meanwhile announced that initial tests on suspected organic sprouts had proved negative. The probes were carried out on a farm in the northern state of Lower Saxony after regional agriculture minister Gerd Lindermann said a link had been found to the main areas hit by the outbreak.
Results available from 23 of the 40 samples of seeds, water, ventilation and work surfaces tested showed they were free of the bacteria responsible for 23 deaths and more than 2,000 people falling ill, the state's agriculture ministry said.
"Investigations are continuing," the ministry said, adding that it did not expect "any short-term conclusions."
German Federal Agriculture Minister Ilse Aigner said Berlin would maintain warnings against eating sprouts as well as tomatoes, lettuce and cucumbers, particularly in the north of the country, until the origin had been pinpointed.
But Andreas Hensel, head of the Federal Institute for Risk Assessment, said that "it is possible we shall never be able to identify the source" of the contamination.
Aigner said investigations were continuing with checks on vegetable supply chains and producers up and down the country.
Klaus Verbeck, who runs the farm in Bienenbuettel, some 80 kilometres (50 miles) south of Hamburg, told the Neue Osnabruecker Zeitung he uses no fertilisers for growing a variety of sprouts and had no idea how they might have been contaminated.
His farm, which produces sprouts for lettuce, azuki beans, mung beans, fenugreek, alfalfa and lentils and receives seed deliveries from several countries, has been ordered closed and all products recalled, authorities said.
"Salad sprouts are grown from seeds and water. They aren't fertilised. And there aren't any fertilisers used elsewhere on the farm," Verbeck said, alluding to the fact the E. coli bacteria may originally have come from animal droppings.
Similar outbreaks in Japan between 1996 and 2003 infected more than 10,000 people and left 22 dead, according to the Japanese health ministry.
The current outbreak has hit at least 14 countries including the United States. Of the 23 victims, 22 died in Germany and one in Sweden -- a woman who had visited Germany.
In Germany, 1,601 patients have been diagnosed as infected and a further 630 with haemolytic uraemic syndrome (HUS), a life-threatening condition involving kidney malfunction, the Robert Koch Institute said.
The rate of infection grew from no more than nine a day during the first 10 days in May, to finally reach a peak of 122 on May 23 and has since slowed, the institute said.