A deadly outbreak of E.coli linked to contaminated cucumbers is sending Europe on high alert, as death toll from the disease climbed to 16 till Tuesday.

So far, 15 people have reportedly died and more than 300 were seriously ill from infections linked to tainted vegetables in Germany. Experts said the numbers are expected to increase in the coming week.

"We hope the number of cases will go down but we fear it will worsen," said Oliver Grieve, spokesperson with the University Medical Center Schleswig where most German victims are being treated.

The German government has identified the pathogen as hemolytic-uremic syndrome (HUS), a serious complication of a type of E. coli known as Shiga toxin-producing E.coli (STEC). The bacteria could damage blood cells and kidneys, and hence cause deaths.

A woman in her 50s was confirmed to be the first fatal victim out of Germany by a local hospital on Tuesday. Officials at the hospital in Boras, southwestern Sweden, said the woman, who had recently traveled to Germany, was admitted on May 29.

Swedish health authorities already said on Sunday that 36 people, all linked to travel in northern Germany, had been confirmed to have infected with E.coli, whereas cases were also reported in France, the Netherlands, Denmark and Britain.

It was the second food scare for European consumers this year. In January, highly toxic dioxin was found in eggs, poultry and pork products across Germany.

German authorities had initially suspected cucumbers imported from Spain to be one possible source of the E. coli outbreak, as three out of four contaminated cucumbers analyzed last week by the Hamburg Institute for Hygiene and the Environment came from Spain.

But officials said they could not determine the exact source of the virulent strain of the bacteria ahead of a crisis meeting in Berlin on Monday.

Nevertheless, parts of the 82-million-populated country have already banned import of cucumber from Spain, while the country's national disease center, the Robert Koch Institute, suggested people avoid eating raw tomatoes, cucumbers and lettuce for a while.

Meanwhile, Spain, clearly on the defensive, insisted that the country was not necessarily the source of the disease and that the cucumbers could have been contaminated during transport to Germany.

"You can't attribute the origin of this sickness to Spain," Spain's Secretary of State for European Affairs, Diego Lopez Garrido told reporters in Brussels on Monday.

"There is no proof and that's why we are going to demand accountability from those who have blamed Spain for this matter," he said.

Frederic Vincent, an EU spokesperson said authorities were currently testing water and soil from the greenhouses that were identified as the source of the contaminated cucumbers.

The results of the tests are expected later on Tuesday or Wednesday, he said.