Poultry in the Tibetan capital Lhasa have tested positive for bird flu, state media said on Tuesday.

The H5 virus was confirmed after birds died at a market on March 1, Xinhua news agency said, quoting China´s agriculture ministry.

The market has been closed and poultry culled to stop the spread of the virus, which experts believe was introduced by migrating birds.

The H5N1 strain potentially deadly to humans was confirmed at a farm near Lhasa in August 2005, prompting a cull of chickens.

Xinhua said three wild birds and two poultry birds tested positive for the H5 virus in the south-western province of Fujian this month, where a woman farmer is critically ill with H5N1.