A Cambodian woman being treated in a Vietnamese hospital died of suspected bird flu Sunday morning, doctors said. If Soc Khol, 25, from Kampot province in Cambodia tests positive for the virus she will be the 12th person to die of bird flu in Vietnam since the virus re-surfaced in late December. She died at 8.45 a.m. (0145 GMT) Sunday in the provincial hospital in Kien Giang, said Nguyen Van Hung, a doctor in the infectious diseases' ward of the hospital. The doctor said that she came from an area where many chickens and ducks had died of bird flu. Khol's 14-year-old brother died mysteriously over 10 days ago after developing a high fever, a bad cough and breathing problems, the doctor said. Khol's test samples were sent to the Pasteur Institute in Ho Chi Minh City for analysis, the doctor said. Bird flu has now spread to 28 of Vietnam's 64 cities and provinces. Around 830,000 poultry have been culled since the start of the year.