"Migrations don't all occur on the same day or even at the same time as they are sometimes affected by either local or seasonal variations in climate," said Robert Hepworth, a UN official who heads the Convention on Migratory Species (CMS).

"So we would need to have a system whereby there was sufficient warning."

World leaders are trying to control a growing outbreak of the HSN1 avian influenza, which has spread to poultry in several Asian and European countries, killing 67 people since late 2003.

In a Reuters interview, Hepworth said scientists, governments and experts across the world had information about migratory birds, but it was inaccessible and not shared.

He said all the information would be collected and centralised in a global computerised system which would constantly update and monitor bird migration patterns, warning countries of any potential threat.

"I think what you'll get is a system whereby there are several stages of alert and warning where we'll be able to provide generic information about particular species which will be arriving at this particular time and may be carrying the virus," Hepworth said.

"We would like to be able to give countries as much warning as possible -- it could be weeks, it could be months."

The system is being set up by the UN Environment Programme (UNEP) and CMS, a treaty concluded under the aegis of UNEP.

The project will gather a team of experts to collect information, maps and charts from national governments, conservation and wildlife bodies.

Hepworth said the main beneficiaries of the system would be developing countries, many of which do not have enough resources to take countrywide preventative action.

"The problem we have in Africa and other developing countries is that the kind of measures that may be appropriate in Europe such as locking up poultry and separating them from wild birds are not practical in these countries," he said.

"The early warning system will actually pinpoint where the higher risk areas might be, so developing country officials can target those specific areas," he said, adding this would be more cost-effective a more general countrywide approach.

The cost of setting up the bird flu early warning system is expected range between $200,000-$300,000, which UNEP and CMS officials say is a small amount compared to the budgets being spent on containing the virus.