Thailand has warned that the death toll from an outbreak of bird flu could be as high as six, amid fears about the virus' spread across Asia.
A grieving father accused the government of a cover-up
Officials said five people suspected of having the virus had died, in addition to a six-year old boy who became the first confirmed fatality on Sunday.
The World Health Organization said the flu's rapid spread posed a potential threat for a serious human outbreak.
However, there has been still been no sign of it jumping from human to human.
A WHO spokesman told the BBC that it was becoming clear that the strain had been around in the region much longer than first thought.
That multiplied the risk of human infections, he added, and of the virus mutating, perhaps by attaching itself to human flu and becoming far more deadly.
The WHO believes the disease is now too serious for individual countries to deal with alone.
Among the Thai dead were two women and three men, according to a statement issued by Thailand's disease control director Charal Trinvuthipong.
Earlier on Monday, the Thai Agriculture Ministry said the virus had been detected in eight more provinces, in addition to two provinces already confirmed.
It said all the fatalities were from two provinces - central Sukhothai and Chachanoengsao, east of the capital Bangkok.
AVIAN FLU ALERT
First jumped "species barrier" from bird to human in 1997
In humans, similar symptoms include fever, sore throat, and cough
Types known to infect humans are influenza A subtypes H5N1 and H9N2
The Thai outbreak has triggered alarm across the region.
In Laos, where thousands of chickens have died, carcasses of dead birds have been sent to Vietnam for tests.
There are also reports of a boy dying of bird flu in neighbouring Cambodia, the BBC's Rachel Harvey reports.
Pakistani officials said a different, and less threatening, strain of bird flu had been found in chickens in the southern port of Karachi.
The strain was identified as H-7 and H-9, less dangerous than the H5N1 afflicting South East Asia.
The six-year-old Thai boy who died is believed to have picked up the virus after touching the carcasses of infected poultry in his village in western Kanchanaburi province.
AVIAN FLU TIMELINE
Nov 2003 - Thailand reports what it calls chicken cholera
15 Dec - S Korea confirms avian flu outbreak
9 Jan 2004 - UN sends help to Vietnam after avian flu outbreak
11 Jan - First Vietnamese death confirmed as avian flu
13 Jan - Japan confirms avian flu outbreak
15 Jan - Taiwan announces different strain of avian flu
21 Jan - Laos reports suspected chicken cholera
23 Jan - Thailand confirms first human cases of avian flu
23 Jan - Cambodia detects first case in chickens
25 Jan - Indonesia announces outbreak
25 Jan - First Thai death confirmed as avian flu
26 Jan - Milder strain of bird flu detected in Pakistan
26 Jan - Five new suspected Thai deaths announced
Thailand's Public Health Minister, Sudarat Keyuraphan, announcing the boy's death, said the boy's health "deteriorated very rapidly".
"This is typical of bird flu. It is very hard to get infected by this disease, but once you have it you tend to go down very fast," she said.
Prime Minister Thaksin Shinawatra, faced with accusations of a cover-up, has admitted that his government initially kept quiet about its suspicions that avian flu had broken out, to avoid causing public panic.
"We have suspected this for about a couple of weeks," he said on Sunday.
"The government knew, so why didn't they tell the public so that we could protect ourselves?" the boy's father, Chamnan Boonmanut, told the Associated Press news agency on Monday.
"Nobody wants to get sick and die," Mr Chamnan said.
As well as Thailand, Vietnam and Indonesia, avian flu has also affected chickens in Cambodia, Taiwan, Japan, and South Korea.
Several countries have banned imports of poultry from Thailand - Asia's largest poultry exporter - including its main customers, Japan and the European Union.
Thailand plans to hold an emergency summit in Bangkok on Wednesday to discuss the crisis with its Asian neighbours. Officials from the EU, the WHO and the UN food agency are also invited.