Bird flu kills two in Vietnam

Some experts think pigs could pass the virus on to humans

Two more people have died from the Asian outbreak of avian flu, raising the death toll to 18.

The latest victims were a six-year-old girl and a 24-year-old man who died in Vietnam's southern Ho Chi Minh City, medical officials said.

Their deaths came amid reports that tests had found H5N1 bird flu in pigs in Vietnam.

But UN experts cautioned the tests were experimental, and a more reliable study had found no infection in pigs.

The UN's Food and Agriculture Organization also stressed that there was no evidence of pigs infecting humans.

Professor Robert Webster, Director of the WHO Collaborating Laboratory on Animal Influenza in Hong Kong, cautioned about the experimental tests, which appeared to detect the H5N1 virus in the nasal cavities of pigs.

"Right now, there is no justification for saying there is H5N1 virus infection in pigs in Vietnam. At this stage nothing has been proven," he said.

Tens of millions of chickens have already died or been slaughtered in 10 Asian countries, but the World Health Organization (WHO) has warned the outbreak was far from being under control.

Health experts say that it is possible that the bird flu virus can jump to humans through some mammals, who have been implicated in human epidemics in the past.

But there has been no evidence of it happening so far.

The human cases of bird flu are generally thought to have been caught from sick birds.

There is no firm evidence of the virus passing from human to human.