Cucumbers from Spain are the source of the recent E. coli outbreak in northern Germany, the Hamburg Insitute for Hygiene announced on Thursday.
The news came after the German Farmers' Association said earlier in the day that domestic produce was most likely not responsible for the outbreak.
German authorities have advised people not to eat cucumbers and generally be careful with raw vegetables.
On Wednesday, initial investigations by the Robert-Koch Institute had suggested that there was "a high probability that [the infections] were caused by consumption of raw tomatoes, cucumbers or green salads," according to a statement released by the German Agriculture Ministry.
The food-monitoring agencies in the northern states had been informed of these findings and were launching appropriate investigations, the ministry said.
The number of current, serious cases of Enterohaemorrhagic Escerichia coli (EHEC) infections was thought to have reached 138 on Wednesday, against a normal annual average of between 60 and 70 cases. Precise figures were impossible to ascertain, as some of the serious stomach infections might have been caused by other bacteria.
The outbreak has spread to Denmark, with one case confirmed by a hospital in Aarhus. The authorities in Copenhagen have announced at least six more potential cases of E. coli infection.
The EU Health Commissioner John Dalli said on Thursday that potential cases in the UK, Sweden and the Netherlands were being investigated.
EHEC is a virulent strain of gut bacterium which can cause stomach cramps and diarrhea, and can lead to anemia and kidney damage in extreme cases. Ordinarily, contaminated raw or undercooked meats or dairy products cause the infection, but the Robert Koch Institute's studies suggest raw vegetables are the more likely cause in this instance.
An 89-year-old woman in the northernmost state of Schleswig-Holstein, who died on Wednesday, was thought to be the second EHEC death, according to preliminary information from the state health ministry.
Three other possible EHEC fatalities were being investigated elsewhere in the country. Authorities confirmed on Tuesday that an 83-year-old woman died of EHEC infection near Hanover.
German Agriculture Minister Ilse Aigner warned against over-zealous reactions amid the outbreak.
Author: Mark Hallam (dapd, dpa, Reuters)
Editor: Nicole Goebel