Seven people have tested positive for the H5N8 virus at a poultry farm in southern Russia.
The pathogen has not been previously reported among humans.
Outbreaks have been reported across the world but are usually found in infected or sick birds.
If infected, the World Health Organisation (WHO) stated the flu can cause death or severe illness among humans.
Scientists at the Vector Scientific Center detected bird flu in December before reporting the human cases to the WHO today.
Anna Popova, head of consumer health watchdog Rospotrebnadzor, said: “Today, I want to inform you about an important scientific discovery made by scientists at the Vector Scientific Center.
“The first cases of human infection with avian influenza A(H5N8) has been laboratory confirmed.”
The cases have now been reported to the WHO for further investigation.
This outbreak comes as the WHO has been forced to act over an Ebola surge in Guinea.
More than 11,000 vaccines have now been sent to the country the WHO’s Africa director, Matshidiso Moeti revealed.
A further 8,600 vaccines will be shipped from the United States to help battle the outbreak.
On February 14, seven peopled fell ill with vomiting, bleeding and diarrhoea.
A further five people have died from the disease following the outbreak.
More to follow…