Russia has banned the import of all fresh vegetables from the European Union as authorities try to determine the source of an E. coli outbreak that has killed 17 people, mostly in Germany.

Russia said Thursday that vegetables already imported from EU countries would be seized. The chief of Russia's consumer protection agency, Gennady Onishchenko, urged his countrymen to “forgo imported vegetables in favor of domestic products.”

He said the E. coli outbreak shows that Europe's health legislation does not work.

About 1,500 people have been sickened by the bacteria. Most of the victims live in Germany or have traveled there recently.

German and EU officials have been unable to find the cause — and origin — of the outbreak. Germany initially pointed to cucumbers from Spain as a possible source of the contamination, but further tests showed that those vegetables were not the cause of the outbreak.

Germany's national disease center says the outbreak started nearly two weeks before the first infections were reported in mid-May. The infection attacks the victims' kidneys, sometimes causing seizures, strokes and comas.

Vegetable growers across Europe say they are suffering major economic losses as the mystery goes unsolved. Spain says it is losing $288 million a week because of import bans and weak demand for the produce, while the Netherlands says it is losing $43 million.

The president of Spain's produce export trade group said that “almost all Europe” had stopped buying Spanish vegetables and fruit.