On Friday, the UN agency called for tighter surveillance of both flocks and humans to quickly detect any further outbreaks after avian viruses were identified in Turkey and Romania.
But in a statement, it said all evidence indicated that the highly pathogenic H5N1 virus still does not spread easily from birds to infect humans.
Experts fear a spread from birds to humans on a larger scale could lead to a mutation in the virus allowing transmission from human to human. This could result in an avian flu pandemic.
"The spread of H5N1 to poultry in new areas is of concern as it increases opportunities for further human cases to occur," the WHO said.
* European Union experts open crisis talks on spread of bird flu, likely to issue recommendations on potential risk for humans.
* World Health Organisation says spread of virus to poultry at fringes of Europe has increased the chances of human cases, but false alarms are likely.
* WHO says all evidence so far shows the H5N1 virus does not spread easily from birds to infect humans.
* WHO says international community must raise about $260 million in the short term to fight bird flu virus in Southeast Asia.
* Results of tests on bird flu samples from Romania are delayed by a day until Saturday because of a customs hold-up. The tests will show whether Romania has the deadly H5N1 strain of the virus, already found in Turkey.
* The spread of bird flu from Asia to Europe is a "troubling sign" and migratory birds will inevitably carry the virus farther, US Health Secretary Mike Leavitt says.
* Seeking to calm fears, Turkish Prime Minister Tayyip Erdogan and French Prime Minister Dominique de Villepin announce separately that they have eaten chicken.
"The early symptoms of H5N1 infection mimic those of many other common respiratory illnesses, meaning that false alarms are likely," it added.
The deadly H5N1 strain has spread to the edges of Europe from Asia, where it has killed 65 people in four countries (Vietnam, Thailand, Cambodia and Indonesia) since 2003.
An H5N1 bird flu outbreak was confirmed on Thursday among birds on a farm in Turkey. An avian virus has been detected in Romanian ducks, but the European Commission said results on whether it is H5N1 or a milder strain were now due on Saturday.
The WHO was sending diagnostic material and other supplies to both countries to support testing in national laboratories.
Romania said it had detected bird flu in the delta of the Danube river, Europe's largest wetlands, which host huge numbers of migrant birds from Russia, Scandinavia, Poland and Germany.
There were some signs of alarm in Serbia, where people were reported to have bought 20,000 face-masks in two days, while Belgrade pharmacies sold out of the anti-viral drug Tamiflu.
In Germany, local media reported that surgeries were being inundated with people seeking vaccination against normal strains of flu, and a surge in private demand for anti-viral drugs.
Poland also reported demand for flu jabs was rising.
"The WHO advises countries experiencing outbreaks in poultry to follow certain precautions, particularly during culling operations and to monitor persons with a possible exposure history for a fever or respiratory symptoms," the agency said.
People are being told to avoid
contact with birds
People in affected countries were advised to avoid contact with dead migratory birds or wild birds showing signs of disease.
Direct contact with infected poultry, or surfaces and objects contaminated by their droppings, is considered "the main route of human infection".
"Exposure risk is considered highest during slaughter, de-feathering, butchering, and preparation of poultry for cooking," it said, adding poultry should be properly cooked.
Experts say the H5N1 strain is mutating steadily and fear it will eventually acquire the genetic changes it needs to spread easily among humans. If it does, they say, it will sweep around the world in months and could kill millions of people.
EU experts opened crisis talks on the spread of bird flu on Friday.
The European Commission said the Brussels meeting would run from 10.30am (0830 GMT) to 8.30pm and examine the risk that migratory birds might pose for the 25-nation European Union.
"The experts' groups will then issue recommendations on the potential risk for humans in contact with such birds," it said in a statement.
"The early symptoms of H5N1 infection mimic those of many other common respiratory illnesses, meaning that false alarms are likely"
World Health Organisation statement
The Turkish and French prime ministers made a point of eating chicken.
No case of the disease among humans has been reported in Europe and the major threat of a human pandemic is still in Asia where the H5N1 virus is endemic, experts believe.
"From a public health point of view, I think what is happening in Southeast Asia is much more serious than what would be happening in Europe where only a couple of hundred people, a couple of thousand people, would be exposed under the proper safety measures," Albert Osterhaus, a top virologist at Erasmus Medical Centre in the Netherlands, said.
Romania is on tenterhooks and has sent bird flu samples to Britain for testing to determine whether the virus found in three ducks in the Danube Delta last week was H5N1, the lethal virus which has killed more than 60 people in Asia since 2003
The samples were supposed to arrive on Thursday but got delayed by customs as they were dangerous material.
Erdogan, Turkish prime minister,
made a point of eating chicken
"The samples are now expected to arrive at the Community Reference Laboratory late on Friday and so results can only be expected by Saturday afternoon, not before," European Commission health spokesman Philip Tod said in a statement.
EU foreign ministers will also discuss bird flu, among other things, at an extraordinary meeting in Luxembourg on 18 October.