On Friday, British officials confirmed a case of bird flu in a parrot that had died in quarantine. The bird was imported from South America.

The bird flu virus was also confirmed Friday in swans found dead in eastern Croatia.

Bird flu had already been detected in Romania, Turkey, and Greece. Romanian officials announced another case Friday, near the border with Moldova.

It was not immediately clear whether the new cases involve the deadly H5N1 strain of the virus.

Several countries are stockpiling anti-viral drugs and stepping up research efforts.

Hungary's health minister, Jeno Racz, announced Friday that a vaccine developed in his country has proven 100 percent effective in humans. He said as many as eight nations have expressed interest in the Hungarian vaccine.