The European Commission on Wednesday said Russia had identified the H5N1 bird flu strain about 200km south of Moscow in the Tula region, next to a lake with numerous wild ducks.
The deadly H5N1 strain - which has killed more than 60 people in Asia since 2003 and forced the slaughter of thousands of birds - has also been discovered in Turkey and Romania.
As European countries geared up their response, Britain said it planned to buy enough vaccine to protect the entire population in case the virus mutates into a strain capable of killing millions of people.
And Germany said it would confine all live poultry to their pens to prevent them from coming into contact with migrating birds, believed by some to be carrying the virus from Asia.
Russia had already said it had bird flu in Siberia and eastern Russia. But Wednesday's announcement marked the first time the virus had spread west of the Ural mountains, which separate Asian from European Russia.
The Russian Agriculture Ministry said 220 domestic fowl died of the disease last week in the village of Yandovka. Authorities imposed a quarantine and ordered the culling of 3000 poultry.
Bird flu has killed some 60
people in Asia since 2003
Romania, where the presence of H5N1 in a Danube delta village was identified last week, said further tests on dead birds from another village had proved positive.
The European Commission says risks of a human influenza pandemic are growing and has advised member states to stockpile anti-viral drugs. Sixteen EU states have placed orders for them.
EU foreign ministers declared bird flu a "global threat" on Tuesday. But on Wednesday, the Stockholm-based European Centre for Disease Prevention and Control (ECDC) sought to calm fears.
"For the time being there is no reason to panic in Europe," Zsuzsanna Jakab, head of the centre, told a news conference. "The risk for citizens to have this virus is minimal."
Scientists fear H5N1 could mutate into a variety that could spread easily between humans if it passes from birds to people on a large scale, but the ECDC saw this as unlikely.
"This virus is not yet adapted to humans. It is not capable of human-to-human transmission and until that happens this will not be a pandemic strain," Jakab said.
Underlining the view of many scientists that bird flu is a far more serious problem in Asia, China said 2600 birds at a poultry farm in Inner Mongolia had died from H5N1.
The World Health Organisation has said the strain is endemic in poultry in China and across much of Asia.