DHAKA (AFP) - Three new farms reported bird flu outbreaks in Bangladesh Sunday after thousands of poultry were destroyed last week due to confirmed cases of the deadly virus, the government said.

On Friday, authorities slaughtered more than 40,000 birds at six farms, a day after official confirmation of a bird flu outbreak on the outskirts of Dhaka.

The outbreak was now suspected to have spread to farms in the north and central parts of the country, government spokesman Abdul Motalib said.

"Today we have detected bird flu in three more farms in the northern district of Jamalpur and destroyed some 9,000 birds there. We will now destroy all the birds within a one-kilometre (0.6-mile) area of the infected farms," he said.

"We also have reports of mass deaths of chickens in central Narayanganj and northern Dinajpur districts. We have sent the samples to laboratories for tests," Motalib said.

Officials confirmed Bangladesh's first case of bird flu late Thursday after samples from one farm near the capital were sent to the National Institute of Animal Health in Bangkok and tested positive for the deadly H5N1 strain of the virus.

The caretaker government has agreed on a string of measures to prevent the spread of the disease in the densely-populated South Asian country of 144 million people.

The H5N1 virus has killed at least 169 people since late 2003, most of them in Asia, according to the World Health Organisation.

Scientists fear the virus could mutate into a form easily spread among humans, leading to a global pandemic with the potential to kill millions.

Bangladesh is home to hundreds of thousands of poultry farms which employ more than a million people.

The country had already banned imports of live birds from more than 50 countries including neighbouring India and Myanmar, after outbreaks were detected there.