The report by the Royal Society for the Protection of Birds (RSPB) and other conservationists found nine of 13 species had decreased in numbers by over 10 percent since previous surveys made between 2015 and 2021.

It follows the current H5N1 strain of Highly Pathogenic Avian Influenza (HPAI) becoming widespread in UK wild bird populations, particularly in seabirds and waterfowl, since the summer of 2021.

It also comes after conservationists warned last year that almost half of the breeding seabird species in the UK and Ireland have declined in the past 20 years, with climate change one of the possible causes.

The RSPB called the latest report "highly concerning" and said reported bird deaths in 2022 "showed that HPAI had become one of the biggest immediate conservation threats faced by many of our seabird species".

The study directly attributed declines for three species -- Gannet, Great Skua and Roseate Tern -- to bird flu.

All three had previously been increasing in numbers in the UK prior to the HPAI outbreak.

The UK is responsible for a high proportion of the global population of Great Skua birds, which saw the biggest fall in its numbers of the trio.

The report concluded the bird flu strain was also "the likely cause" of dwindling numbers of Sandwich and Common Terns.

Further work is needed to better understand the potential role of HPAI in the numbers recorded of the remaining species, which include various gulls, Arctic Skua, Kittiwake, Arctic Tern and Guillemot.

"This new study shows that bird flu can be added to the long list of things that are devastating our seabirds," the RSPB's director of conservation, Katie-jo Luxton, said.