Pakistan has culled around 40,000 chickens at six farms near the capital Islamabad where bird flu has been detected, officials said yesterday.

Pakistan reported its first case of the deadly H5N1 bird flu at two farms in the North West Frontier Province (NWFP) in February and found the virus at other farms near Islamabad last week.

Scientists detected a mild strain of bird flu, H5, in flocks at six farms in Sihala, Tarlai and Ali Pur Farash areas in the outskirts of Islamabad, said Dr Afzal, commissioner at the state-run Animal Husbandry.

Afzal said that a large number of more samples had been taken from other farms to carry out tests. "Immediate action is taken if we suspect any bird flu virus in any farm," he added.

Another official has said that the bird flu is fast spreading from farms in Islamabad to the nearby city of Rawalpindi.

"The outbreak of H5 strain has now been spread to 12 farms," said Dr Muhammad Sham, director at the state-run Poultry Development Research Center.

Sham said that fears about the bird flu spread are high and special teams have been formed to cull and bury the affected chickens and disinfect the affected farms.

He asked owners of farms not to allow wild bird mixed with chicken. He warned that the virus could affect human being if pre-cautionary measures were not taken.

Despite the outbreak of bird flu cases in parts of Pakistan, no case of human avian flu has been detected so far, according to Health Secretary Anwar Mehmood.

He said that 25 samples had been sent for bird flu tests following identification of the H5N1 strain at some poultry farms near the federal capital on April 16. But their test results were negative.

The World Health Organization has also agreed with Pakistan's notion that no human avian flu has been detected but has advised the Pakistani government to cull all chickens at the poultry farms within a three-kilometer radius of the farms where the bird flu virus had been confirmed.