The deadly H5N1 virus first surfaced in Asia but appears to be spreading quickly to the west on the wings of migrating birds. There are fears that Africa, where many countries have poor health systems, could also soon report cases in birds.
The European Union was poised on Tuesday to ban imports of captive wild birds after a parrot died of the H5N1 strain in Britain. The ban could initially last a month, the bloc's health chief said.
The European Commission also planned to tighten rules on people bringing their own pet birds into the EU.
The EU halted imports of live birds and some poultry from Croatia, where authorities started to slaughter 10,000 birds on Tuesday, a day after Russia confirmed more bird flu in poultry and Slovenia tested a dead swan for the virus.
France ordered poultry farmed in more than one fifth of the country to be kept inside over concerns that migratory wildfowl could spread bird flu to the country. Markets, fairs and displays featuring wild birds would be suspended.
Some experts believe the first human-to-human mutation of H5N1 is likely to occur in Asia, where 62 people have died since late 2003. No human infections have been reported in Europe.
"Europe is a minor side-show to what is really going on," said Roger Morris, an expert on the spread of the disease at Massey University in New Zealand.
Farmers in Asia often live close to birds and livestock, making it much easier for humans to be infected with the virus.
Indonesia's Health Ministry said on Tuesday that tests had confirmed that a man who died in September was positive for bird flu. Seven people in total have been infected with H5N1.
In China's latest outbreak, hundreds of farm geese died in the eastern province of Anhui, Noureddin Mona, of the UN Food and Agriculture Organisation (FAO), told Reuters.
He said the Agriculture Ministry had told him on Monday that 2,100 birds had been infected, 550 had died and 45,000 culled.
The H5N1 strain first surfaced in humans in 1997 in Hong Kong and reappeared in South Korea in 2003. It has since spread throughout much of East and Southeast Asia, infecting 121 people and killing nearly half of them.
The World Health Organisation has said the H5N1 strain is endemic in poultry in China and across much of Asia, and it might only be a matter of time before it develops the ability to pass easily from human to human.
In Hong Kong and Taiwan, exotic bird markets are largely empty over customers' fears about catching avian flu after birds in a smuggled cargo from China were found to have H5N1. The FAO's head said the world must focus on Asia, and on stopping the virus passing between birds.