A deadly E.coli outbreak linked to cucumbers is expected to worsen in the coming days, a scientist says. Fourteen people have died in Germany and hundreds are ill from infections linked to contaminated vegetables. "We hope the number of cases will go down but we fear it will worsen," said Oliver Grieve, of the University Medical Centre Schleswig-Holstein, where many victims are being treated. It is thought cucumbers from Spain were at the origin of the outbreak. But Spanish officials have refused to accept the blame, saying it is still unclear exactly when and where the vegetables were contaminated. The World Health Organisation has described the outbreak as "very large and very severe" and has urged countries to work together to find the source of contamination. Travel link Robert Koch Institute (RKI), Germany's national disease institute, has confirmed 329 cases in the country - though some reports have mentioned as many as 1,200 cases. Professor Mark P Stevens of The Roslin Institute explains what is E. coli O157 In Sweden, authorities said there have been 36 suspected E.coli infections, all linked to travel in northern Germany. Cases have also been reported in Switzerland, Denmark, the Netherlands and the UK. In many instances, the gastrointestinal infection has led to Haemolytic-uraemic Syndrome (HUS), which causes kidney problems and is potentially fatal. Suspicion has fallen on organic cucumbers from Spain imported by Germany but then re-exported to other European countries, or exported directly by Spain. Cucumbers from the cities of Almeria and Malaga have been identified as possible sources of contamination, according to an EU spokeswoman.