Lyubov Voropayeva, spokeswoman for the Russian Agency for the Supervision of Consumer Rights, said Thursday the ban has been imposed immediately for no definite period of time.

Russia banned fresh imports from Spain and Germany on Monday, warning that the sanction could soon cover all EU nations if there was still no explanation on the source of the disease and how it is being spread.

Researchers are still not able to pinpoint the cause of the outbreak that has hit Germany and other European nations, leaving some 1,500 people infected.

No fatalities or infections have yet been reported in Russia.