A senior director of the World Health Organization has warned that a failure to respond quickly to bird flu could have immeasurable global consequences.
Scientists fear Asia will bear the brunt of future outbreaks
Dr Shigeru Omi told a conference in Tokyo that despite the best efforts of many governments, the threat of a pandemic was continuing to grow.
The conference is seeking ways to prevent the spread of the virus.
The warning came as the UN said $1.5bn (£850m) was needed to help fight the disease and prepare for a pandemic.
The UN bird flu co-ordinator, Dr David Nabarro, said he hoped the funds would be pledged at an international donors summit to be held in Beijing on 17 and 18 January.
He said the $1.5bn would be used for bird vaccination programmes, getting enough vets trained, and to prepare for the possibility of a human pandemic in which bird flu is passed from human to human.
The UN's Food and Agriculture Organisation earlier warned that bird flu could become endemic in Turkey and pose a serious risk to nearby and neighbouring countries - many of which are now taking preventative action.
Two people have died of the disease in Turkey, and more than 70 have died worldwide since the latest outbreak started in late 2003.
Meanwhile initial tests suggest that a 29-year-old woman from Indonesia has also died of the disease, which could bring the number of deaths there to 13.
East Asia focus
Public health officials and ministers from across Asia are attending the Tokyo conference, which aims to put in place a rapid response strategy to contain an outbreak of avian flu.
Dr Omi said that despite recent deaths in Turkey, the main risk of a serious outbreak was focused on East Asia.
He said health officials should respond "with all the weapons at our disposal" should there be a pandemic.
"If we can achieve this rapid response, we may have a good chance of halting the spread of the virus before the situation becomes uncontrollable, or at least of slowing it down.
"But if we fail, the consequences for societies, economies and global public health could be immeasurable."
Meanwhile WHO officials in Turkey are examining how bird flu moved so quickly across the country since two people died in the eastern province of Van last week, and why there have been so many cases.
Victims appeared to have contracted the virus from close contact with infected poultry. But the WHO admits it may be too soon to confirm any changes in the virus and its spread.
So far there has been no evidence of the virus being passed from human to human.
The WHO thinks the world is now closer to another flu pandemic than at any time since 1968, when the last of the 20th Century's three pandemics occurred.