The outbreak of the deadly H5N1 virus, which began March 1 in Lhasa's Chengguan village, killed 680 chickens and prompted the culling of 6,990 birds, The Associated Press said today, citing Xinhua news agency.

The Beijing Youth Daily reported yesterday that the market has since been shut down and authorities were trying to determine the source of the infection. It was possible that the chicken were infected through contact with migrating wild birds, it said.

The government report, submitted by China's Ministry of Agriculture, also gave details of five H5N1 bird flu outbreaks among migratory birds in Tibet and neighboring Qinghai in April and May of last year. The five outbreaks killed 3,648 birds, including bar-headed geese, brown-headed gulls, crows, hawks and other wild birds, it said.

Xinhua reported on the earlier outbreaks last year but did not give specific details.

Qinghai is a known transit point for migratory birds, and the virus killed thousands of bar-headed geese at a nature reserve in the province in mid-2005, raising fears that the virus was on the move, jumping among hosts in the wild.

Last week, China reported a new human case of bird flu in the coastal province of Fujian, where a 44-year-old farmer surnamed Li was diagnosed on February 18 after she developed a fever and began coughing.

It was the mainland's first human case of bird flu since January 10, when the government said a 37-year-old farmer in Anhui province in eastern China had contracted bird flu but had recovered.

The H5N1 bird flu virus has killed at least 167 people worldwide since it began ravaging poultry stocks across Asia in late 2003, according to the World Health Organization.

Experts fear that the H5N1 virus may mutate into a form easily passed between humans, sparking the world's next deadly pandemic.