Fenugreek seeds imported from Egypt and linked to a deadly strain of E.coli in Germany were grown at the farm where authorities are almost certain the outbreak started, a German health official said on Friday.
"The farm received the fenugreek seeds from Egypt," said Gert Hahne, the spokesman for the agriculture ministry in Lower Saxony, where the farm is located.
But much is still uncertain and scientists are still working to clarify how and from where the bacteria entered the food chain in Europe, going on to kill 49 people so far.
The farm in the northern German village of Bienenbuettel is at the heart of the deaths and received the seeds from a German trader, which has also been linked to a smaller E.coli outbreak in France, the German Institute for Risk Assessment (BfR) said.
Egyptian agricultural quarantine chief Ali Suleiman rejected European conclusions that deadly seeds originated there: "The bacteria's presence in Egypt has never been proven or recorded until now," Suleiman said, according to state news agency MENA.
The European Centre for Disease Prevention and Control (ECDC) and the European Food Safety Authority (EFSA) said on Wednesday that initial investigations implicated the seeds, imported from Egypt, in the German and French outbreaks.
But European food and health officials said there was still "much uncertainty" about whether the seeds from Egypt were "truly the common cause of all the infections" as there were currently no positive bacteriological results.
The rare and highly toxic strain of E.coli has killed at least 49 people since early May, all but one in Germany.
More than 4,100 people in Europe and in North America have been infected. Almost all lived in Germany or had recently travelled there.
The strain of E.coli infections in the current outbreaks -- known as STEC O104:H4 -- can cause serious diarrhoea and, in severe cases, kidney failure and death.