Tests have confirmed that a chicken found dead in Albania had the lethal H5N1 strain of bird flu.
The Albanian case was found in a domestic chicken
The chicken was found in the village of Cuke, 50km (31 miles) from the border with Greece, which has also had cases.
Officials have been sent to the affected region to carry out further tests and a disinfection operation.
Four new cases of bird flu have also been confirmed in wild ducks in Sweden, but it is not yet clear whether they are the H5N1 strain.
Samples have been sent to the European Union reference laboratory in the UK for further testing.
H5N1, which has killed at least 95 people since late 2003, mostly in Asia, has been found in a number of other European countries, including Greece, Serbia and Bosnia.
Earlier this week, Austria said it had detected the strain in several live cats days after it was detected in a dead cat in Germany.
That case was thought to be the first example outside Asia of the virus crossing species to infect a mammal.
The virus has also spread for the first time to Poland, while Serbia says it has detected the strain in dead swans and has sent samples for further tests.
The H5N1 virus can be caught by humans who handle infected birds, but it is not yet known to have passed from one person to another.
However, experts fear the virus could mutate to gain this ability, and in its new form trigger a flu pandemic that could kill millions.