Scientists said two pigs on the Indonesian island of Bali had become infected with the bird flu virus, again raising concerns the deadly flu virus could become transmissible between people.

Speaking at a China-Japan infection prevention conference in Guangzhou, a leading Chinese medical expert said the pigs generated a variant of the bird flu virus after they contracted bird flu.

The pigs acted as a kind of mixing vessel in which genetic material from avian flu viruses combined with other influenza strains, said Zhong Nanshan, a renowned medical expert and academician with the Chinese Academy of Engineering.

Some pig organs are similar to human organs, suggesting that a similar mixing of flu genetic material could occur in humans, said Zhong.

The best way to prevent bird flu is to dispose of infected birds as quickly as possible, establish stringent quarantine requirements and treat human patients rapidly, Zhong said.