Russia has banned the import of all fresh vegetables from the European Union because of the E. coli outbreak centred on Germany.
The country's chief medical officer said EU-produced vegetables would be seized across Russia.
More than 1,500 people have been infected by enterohaemorrhagic E. coli (EHEC), which can cause the deadly haemolytic-uraemic syndrome (HUS).
Seventeen people have died - 16 of them in Germany and one in Sweden.
Earlier suggestions that infected Spanish cucumbers were the source of the outbreak have now been discounted, with German health officials admitting they do not know where this particularly virulent strain of of E.coli has come from.
The EU said the Russian ban was "disproportionate" and would be lodging a protest, European Commission spokesman Frederic Vincent said.
BBC Moscow correspondent Daniel Sandford says more than a quarter of all the vegetables exported from the European Union go to Russia, making it the single biggest export market for EU farmers.
Russia banned vegetable imports from Germany and Spain earlier this week.
Consumer protection agency head Gennady Onishchenko announced the the extension of the ban to cover fresh vegetables from anywhere in the European Union.
He said orders to stop all incoming European vegetable shipments had been issued to Russian customs authorities, adding: "I call on people to forgo imported vegetables in favour of domestic products."
He criticised food safety standards in the EU.
"This shows that Europe's lauded health legislation - one which Russia is being urged to adopt - does not work," he said.
Hamburg cluster
The head of the German public health body tackling the E. coli outbreak says it may be months before it stops, depending on whether infected food is still in warehouses and whether the original source is still active.
Reinhard Burger, president of the Robert Koch Institute, told the BBC "we may never know" the infections' source.
At least 365 new E. coli cases were reported on Wednesday, a quarter of them involving HUS, a condition associated with bloody diarrhoea and kidney failure, the Robert Koch Institute said.
The new cases include two in the US, both of whom had recently travelled to Hamburg, where many of the cases are clustered.
Spain is seeking compensation after German authorities initially alleged a link between Spanish vegetables and the deadly strain of bacteria, causing sales to collapse.
The loss of earnings for affected farmers in Spain has been estimated at more than 200 million euros ($290 million) per week.
The European Commission lifted its warning over the Spanish cucumbers on Wednesday, saying tests "did not confirm the presence of the specific serotype (O104), which is responsible for the outbreak affecting humans."
Spanish Prime Minister Jose Luis Rodriguez Zapatero said Spain would "seek reparations before the relevant authorities in Europe".
In an interview with Spanish national radio, he said: "Yesterday, it became clear, with the analyses carried out by the Spanish agency for food safety, that there is not the slightest indication that the origin of the serious infection is any Spanish product.
"Now we have a very ambitious task ahead of us, which is to recover our good reputation as soon as possible and the trade in all Spanish products."
Mr Burger said German authorities had tried to balance risks when they wrongly blamed Spanish farms. He said the authorities had to act quickly - even though the conclusion later turned out to be wrong.
"We wanted to avoid new infection sources. It's a difficult balance," he said. "You don't want to wait a long time and on the other hand you don't want to cry wolf."
In addition to Germany, cases of EHEC have also been reported in eight other European countries - Austria, Denmark, the Netherlands, Norway, Spain, Sweden, Switzerland and the UK.
Virtually all the sick people either live in Germany or recently travelled there.
Several countries have taken steps to curtail the outbreak, such as banning cucumber imports and removing the vegetables from sale.
Health authorities have also advised people to wash fruit and vegetables thoroughly, to do the same with all cutlery and plates, and to wash their hands before meals.
