Three more countries said on Tuesday they had detected cases of deadly bird flu in wild swans, with Germany, Iran and Austria the latest to find the virus that has killed 91 people worldwide.

Austria and Germany became the third and fourth European Union countries to report H5N1 bird flu, just three days after the bloc´s first instances were confirmed by Italy and Greece.

Germany said its results came from initial tests. Both countries said samples of the dead birds had been sent to the EU´s reference laboratory in Britain for confirmation. Experts had said it was only a matter of time before the H5N1 strain dangerous to humans broke out in Iran, a wintering place for wildfowl that may be carriers. Neighbouring Iraq, Azerbaijan and Turkey had already reported outbreaks.

The highly pathogenic H5N1 strain of the virus has killed at least 91 people in Asia and the Middle East, according to the World Health Organisation.

Experts fear H5N1 may mutate into a form that can spread between people and cause a pandemic that could kill millions.

New cases of H5 bird flu were found in Romania, Europe´s largest wetlands and a major migratory route for wild birds.

Tests were under way in Britain to see if the new samples were H5N1, of which Romania and neighbour Bulgaria have already had cases.

Germany said it would bring forward to Feb. 17 a ban on keeping poultry outdoors, and Italy said police had impounded more than 80,000 chickens and 7,000 eggs from farms in the south that were not respecting health norms.