Germany on Friday blamed sprouts for a bacteria outbreak that has left at least 30 dead and some 3,000 ill, and cost farmers across Europe hundreds of millions in lost sales.
"It's the sprouts," Reinhard Burger, the president of the Robert Koch Institute, Germany's national disease centre, told a news conference on the outbreak of enterohaemorrhagic E. coli (EHEC) in northern Germany.
"People who ate sprouts were found to be nine times more likely to have bloody diarrhoea or other signs of EHEC infection than those who did not," he said, citing a study of more than 100 people who fell ill after dining in restaurants.
As a result, the government lifted a warning against eating raw tomatoes, lettuce and cucumbers.
The advisory, first issued over two weeks ago, has cost vegetable growers in Europe hundreds of millions of euros (dollars) in lost sales and sparked diplomatic spats across Europe.
German authorities had initially pointed the finger at cucumbers imported from Spain as the origin of the outbreak. But they later retracted the statement based on subsequent tests, infuriating Madrid and sparking threats of lawsuits.
And the European Union blasted Russia for imposing a "disproportionate" blanket ban on vegetable imports from the 27-nation bloc.
In an attempt to help hard-hit farmers, the EU has offered to pay out 210 million euros ($303 million) in compensation.
The origin of the contamination is believed to be a small organic farm in Lower Saxony which first came under suspicion at the weekend, Burger said.
"Tests carried out at the farm have proved negative", but evidence still pointed to the farm as a probable source of contamination, he added.
"Thousands of tests carried out on tomatoes, cucumbers and lettuce have proved negative. But there are ever more signs of a link between people contaminated and a farm" growing a variety of sprouts, a government official told AFP on condition of anonymity.
"The links are ever clearer. It's a hot lead," he said.
Lower Saxony agriculture minister Gert Lindemann said earlier this week that experts had found no traces of the E. coli bacteria strain at the farm but he did not rule it out as the source of the contamination.
In an interview to be published in next week's edition of Focus magazine, Lindemann said some 60 of the people contaminated had eaten sprouts from the small farm in Bienenbuettel which employs about 15 people.
Contamination might have been caused by infected seeds or "poor hygiene", he added.
Three of the farm's employees also fell ill last month, suffering from diarrhoea, he said.
The outbreak is believed to have started at the beginning of May, with the first people falling ill in the second week of May, the Robert Koch Institute said.
To date, more than 2,800 people have fallen ill in Germany, it added although other estimates have put the number higher.
People in at least 14 countries were sickened by the outbreak, most of them having recently visited northern Germany where over 75 percent of the cases have been registered, most of them among women.
At least 30 people have also died, according to regional authorities, all but one in Germany. A woman who had visited Germany died in Sweden.
"The number of new infections is declining," Burger told the news conference Friday following announcements of a drop in cases earlier this week.
But he warned that the "outbreak is not yet over", saying that some people were still falling ill after being contaminated several days ago.