HANOI (Reuters) - Doctors suspect bird flu may have killeda four-year-old child in northern Vietnam, state-run radio saidon Wednesday.

A Health Ministry official told a government meeting onTuesday the child had a fever and serious pneumonia aftereating chicken which died of unknown cause in the mountainousprovince of Son La, the Voice of Vietnam radio said.

It said the child died in a hospital in Hanoi but gave nogender. Doctors were testing to see if the H5N1 bird flu viruswas the killer, the ministry official was quoted as saying.

Vietnam last reported outbreaks among poultry in October,but Son La was not on the government's bird flu watchlist.

The H5N1 virus killed four of the seven Vietnamese who havecaught it this year, taking the country's death toll since late2003 to 46. The last death was reported in August.

Health officials had worried that winter in northernVietnam might trigger a new wave of outbreaks among poultry asthe virus seems to thrive best in cool temperature.

The Agriculture Ministry said 63 of Vietnam's 64 provinceshad been vaccinating birds against the virus this year.

The H5N1 virus remains mainly a virus of birds, but expertsfear it could mutate into a form easily transmitted from personto person and sweep the world, killing millions.

Globally, the H5N1 virus has killed 209 people out of 340known cases and most of the deaths are in Indonesia, followedby Vietnam, World Health Organisation figures show. Hundreds ofmillions of birds have died or been slaughtered.

(Reporting by Ho Binh Minh; Editing by Michael Battye andSanjeev Miglani)