BANGKOK, Feb 15: A 13-year-old boy has died of bird flu in Thailand, taking the death toll from the virus rampaging through Asia to at least 20, a health ministry official said on Sunday.

"He died last night of respiratory failure," Dr Charal Trinwuthipong, chief of the Department of Disease Control, told Reuters. The virulent H5N1 bird flu has spread to eight Asian nations, killed 14 Vietnamese and six Thais and devastated the poultry industry.

The 13-year-old boy was believed to have caught the disease through contact with sick chickens, officials said. The other Thai deaths - four boys aged between six and seven and a 58-year-old woman - are also thought to have had contact with infected poultry.

Fears persist that the bird flu virus could combine with a human flu virus to become a deadly disease that can spread among people. Now there are concerns the virus may have leapt to exotic animals.

Experts say the virus, which has forced the slaughter of some 80 million birds in the region, mostly in Vietnam and Thailand, is probably spread by migrating birds.

The United Nations has warned Asian countries not to relax in the war on a bird flu virus because the epidemic was still spreading in Cambodia, China, Indonesia and Laos.

The UN Food and Agriculture Organisation (FAO) has stressed that poorer Asian countries had neither the resources nor the organisation to eradicate the fast spreading H5N1 virus, reflecting the fears of experts that it could flare again.

Thailand has slaughtered 30 million poultry to eradicate the virus and says it is killing the last birds in its last epidemic zone. With an eye on its embattled $1 billion-a-year export trade in chicken, Thailand is pressing overseas customers like Japan and Europe to test its birds for the virus in an effort to shorten import bans that had devastated the industry.

Prime Minister Thaksin Shinawatra, whose government was accused of an initial cover-up of the outbreaks, said he expected the country to be clear of bird flu by the end of the month. -Reuters