Scientists are trying to identify the source of a virulent strain of E.coli which has claimed 10 lives in Germany.
It has become a major public health emergency - one of the largest outbreaks of its kind recorded.
The bacterium is suspected of infecting hundreds of people in Sweden, Denmark, the Netherlands and Britain, and the suspicion has fallen on organic cucumbers imported from Spain.
People have become ill with hemolytic-uremic syndrome, an aggressive form of E.coli known to cause kidney failure and affect the central nervous system, the BBC reports.
Two deaths have been officially attributed to E. coli. The latest cases were three women in their 80s and a fourth in her 30s.
The German government has advised people to stop eating cucumbers, tomatoes and lettuce. Most of the victims have come from northern Germany in the area around Hamburg.
Food safety authorities in Austria and the Czech Republic have also ordered the recall of organically grown vegetables supplied by a Spanish producer, which is one of the suspected sources of the outbreak.
A spokesperson for the European Union said two greenhouses in Spain identified as sources had ceased their activities.
They were now being investigated to see whether the contamination occurred in Spain or elsewhere.