The virus was discovered at a poultry farm run by security forces, three days after it was found at another farm in the port city, Agriculture and Livestock Ministry official R.H. Usmani said.

'We have found H5N1 virus in the second farm too this morning,' he told AFP, adding that both farms have been sealed off and officials have culled around 10,000 chickens.

A spokesman for the paramilitary Rangers force which owns the farm said they had alerted authorities and destroyed infected poultry and feedbags after hundreds of chickens were found dead.

'We have shifted nine of our workers to a hospital and doctors are monitoring them in an isolation ward,' said the spokesman, Maj Asad Ali.

Another three poultry handlers from the other farm where the virus was discovered last week have also been placed in an isolation ward at a local hospital, medical officials said.

'Our doctors are observing all the farm workers and have so far found no signs of transmission of the dangerous virus in any of them,' Sindh province health secretary Abdul Majid told AFP.

'We are on the highest alert and our teams are monitoring all the places where the poultry industry is concentrated,' he said.

Pakistan recorded its first death from bird flu in December when a man died in North West Frontier Province bordering Afghanistan. The victim's brother also died before being tested for the virus. Another five people were infected but recovered.

Worldwide, the H5N1 virus has killed more than 200 eople -- AFP