XINING, May 21 (Xinhua) -- Northwest China"e;s Qinghai Province is still on alarm Thursday, four days after an H5N1 avian flu outbreak was confirmed in one of its Tibetan counties, the local animal epidemic prevention authority said.

    Altogether 121 migratory birds were found dead near the Genggahai Lake of Gonghe County in the Tibetan Autonomous Prefecture of Hainan on May 8. They tested H5N1 positive at China"e;s National Avian Influenza Reference Laboratory on Sunday.

    As of Wednesday, the number of dead birds had climbed to 200, the provincial animal epidemic prevention and treatment department said in a press release.

    It said Gonghe County had killed 21,000 poultry and vaccinated another 23,000 to avoid infection, though no signs of bird flu had been observed on any farm so far.

    The department has sent a team of specialists to help contain the outbreak in Gonghe.

    The epidemic area has been sealed off as of Sunday. Four temporary checkpoints were set up on roads leading to the area to disinfect every passing vehicle and allow only epidemic prevention workers to enter.

    Gonghe County, with 133 hectares of wetland, is a major stopping-off point for migratory birds.