Afghanistan, India and Myanmar said tests had now confirmed H5N1 caused recent outbreaks in birds, while Malaysia reported two new cases in a wild bird and dead chickens.
Denmark, the latest European country affected, said tests showed a wild buzzard found south of Copenhagen had H5N1.
Israel suspects bird flu killed turkeys on two farms in its southern Negev region although there were no test results yet, Zeev Boim, the agriculture minister, said. Israel has so far been spared the virus.
Swiss drug maker Roche said it was boosting output of its flu drug Tamiflu by a third. Tamiflu is seen as one of the most effective methods of treating people infected with H5N1.
In India, veterinary workers began throttling more than 70,000 birds to try to control the latest outbreak there. Hundreds of people were also tested for fever.
"There is no time for niceties. The birds have to be killed as fast as possible," said Bijay Kumar, animal husbandry commissioner of the state of Maharashtra, where bird flu resurfaced this week in backyard poultry.
Bird flu has spread with alarming speed in recent weeks across Europe, Africa and parts of Asia, leaving some impoverished nations such as Afghanistan and Myanmar appealing for protective clothing and other basic equipment.
The more it spreads, the greater the fears of the virus mutating into a form that could easily pass from one person to another, triggering a pandemic in which millions could die.
"There is no time for niceties. The birds have to be killed as fast as possible"
Animal husbandry commissioner in the Indian state of Maharashtra
Although hard to catch, people can contract bird flu after coming into contact with infected birds.
Three young women who died in recent weeks in Azerbaijan, on the crossroads between Europe and Asia, are thought to be the latest human victims of the virus. If confirmed as caused by H5N1, the deaths would take the human toll to over 100.
In Serbia, a teenager from a bird flu-stricken area was put in isolation after developing a high fever that could be a symptom of the disease, the country's chief epidemiologist said.
"The boy is from the family where we found a rooster with clinical symptoms of bird flu," Predrag Kon said, adding he would be kept in isolation for 72 hours or until the possibility of bird flu had been ruled out.
So far, no human cases have been reported in India, Afghanistan, Myanmar or Malaysia but hundreds of people near India's latest outbreak in western Maharashtra state have complained of fever. Doctors say they are most likely suffering from dengue but further tests are being done.