Three UN agencies on Wednesday warned that an ongoing rise in avian flu outbreaks globally raised concerns that the virus might adapt to infect humans more easily, and urged countries to strengthen disease surveillance and improve hygiene at poultry farms.

Earlier this year, a new H5N1 strain of bird flu that is highly contagious among wild birds explosively spread to new geographical regions, infecting and killing a variety of mammal species and raising fears of a pandemic among humans.

However, only about half a dozen cases in people who had close contact with infected birds have been reported to the World Health Organization (WHO), and most of those have been mild.

"We encourage all countries to increase their ability to monitor these viruses and to detect any human cases," said Dr Sylvie Briand, the director of epidemic and pandemic preparedness and prevention at the WHO.

The WHO, along with the United Nations' Food and Agriculture Organization and the World Organisation for Animal Health said countries should work together across sectors to save as many animals as possible and to protect people.

The agencies also noted that countries need to share genetic data of viruses from humans and animals in publicly accessible databases.

About ten countries have reported cases of avian flu outbreaks in both land and sea mammals since 2022, including in farmed mink in Spain, seals in the United States of America, and sea lions in Peru and Chile.