Hospital sources in Vietnam have announced that two people showing symptoms of bird flu have died in the last week.
A third person suspected of being infected is undergoing treatment.
Meanwhile the World Health Organisation is pressing China to provide information on the death of a young girl who it was initially thought might have contracted the virus.
China has reported no human bird flu infections since the lethal H5N1 strain surfaced in Asia two years ago.
When the girl died however, suspicions were raised.
But authorities insist she was a victim of pneumonia.
Beijing was accused of covering up the extent of the respiratory virus SARS which has killed around 800 people worldwide.