"The results of laboratory tests confirmed that it's the H5N1 virus, found in 2,000 chickens raised for their eggs," a livestock department official said.

"Those chickens were culled on January 20," she added.

Thailand reported its first outbreak of the year on January 15, after finding the virus in ducks in the central province of Phitsanulok.

Thailand has been among the countries hardest hit by the deadly H5N1 strain of the virus, recording 25 human cases, 17 of them fatal, since the outbreak began here in 2004.

The last bird flu fatality was in August last year, when a 59-year-old farmer in northeastern Thailand succumbed to the virus.

Thailand was criticized for being slow to respond to the outbreak of bird flu, but now is considered one of the countries best prepared to battle the disease. It aims to be completely free of the virus in three years.

Thailand has stockpiled 1.5 million capsules of the anti-viral drug oseltamvir, a generic version of the drug Tamiflu, which the kingdom began producing this year.

Bird flu has badly hurt Thailand's poultry industry, once the world's biggest, after countries around the world slapped bans on raw Thai chicken after the 2004 outbreak.

Thailand, the world's fourth-largest exporter of poultry, now only exports cooked chicken.