Two more people died in Vietnam of bird flu, taking Asia's death toll today to 18, but UN agencies dismissed earlier reports that the virus had spread to pigs.
A day after China said bird flu had spread to more provinces and UN agencies chided Asian countries for being slow to sound the alarm, a Food and Agriculture Organisation official in Vietnam said three or four pigs had tested positive for the virus.
That was a worrying development since the immune system of pigs is similar to that of humans but a FAO scientist in Rome said the tests referred to were not upto standard.
"The news that he reported was based we believe on studies with an experimental test," Mr Peter Roeder, a FAO animal health expert, told reporters.
Mr Robert Webster, a World Health Organisation animal flu expert, added: "Right now there is no justification for saying there is H5N1 virus infection in pigs in Vietnam."
Scientists say pigs are ideal vessels for mixing genes from the bird flu pathogen and the human influenza virus.
The WHO has said this could result in the emergence of a new subtype of virus for which humans would have no immunity.
"If there was a very widespread infection in pigs, then that would be a great concern that a pandemic strain might develop from it," Ms Jacqueline Katz, a flu expert at the US Center for Disease Control and Prevention, said last week.