At least half a million chickens have been either killed by a bird flu outbreak in Burkina Faso or culled to prevent the virus spreading, the West African country announced Saturday.

The outbreak of the highly pathogenic H1N1 strain of avian flu was detected late last year at 42 farms spread across seven regions in the centre and west of the country, Animal Resources Minister Moussa Kabore told a press conference.

"At the end of December 2021, we noted a high mortality rate among poultry at our country's production sites," Kabore said, adding that tests had confirmed the presence of H5N1 bird flu.

By January 7, around 500,000 chickens had either died of the disease or culled and 1.3 million boxes of eggs had been destroyed, he added.

The government has announced several measures to try stamp out the disease, including monitoring spots where wild birds gather for possible cases and capturing and testing sick or dead birds for the virus.

Burkina Faso has been hit by successive waves of bird flu since the H5N1 strain swept the globe in 2006.

In most cases the outbreaks have been blamed on migratory birds.

Livestock-rearing is one of Burkina Faso's biggest industries and its third-largest foreign exchange earner, after the production of gold and cotton.

Poultry is particularly popular, with many households raising chickens for their own consumption or as a way of making money.