Zagreb, Croatia ? Authorities in Croatia began killing thousands of domestic birds Saturday and ordered disinfection for a large area near a national park where six swans were found dead from bird flu.

Elsewhere, Russia reported a new outbreak of a lethal strain of bird flu, Sweden confirmed a case, and Italy and Congo became the latest countries to ban imports of poultry from nations affected by the virus.

The virus is spread by migrating wild birds and has recently been found in birds in Russia, Turkey and Romania, spurring efforts around the globe to contain its spread.