Russian authorities say they have detected what is believed to be "human infection with avian influenza H5N8," the World Health Organization (WHO) has confirmed to CNN.

Russia notified WHO of the possible strain. "If confirmed, this would be the first time H5N8 has infected people," a WHO Europe spokesperson said in a statement Saturday.

The reported cases were workers exposed to bird flocks, according to preliminary information, the statement added.

The workers were "asymptomatic and no onward human to human transmission was reported," the spokesperson said.

Speaking during a televised briefing on Saturday, Anna Popova, the head of Russia's Federal Service for Surveillance on Consumer Rights Protection and Human Wellbeing, said that the strain had been detected in seven poultry farm workers in the south of the country, state-run news agency TASS reported.

While still not confirmed by the WHO, the Russian health authority has said it is in discussion with national authorities to gather more information and "assess the public health impact" of the incident.

Avian flu usually affects only birds and there are many different strains of it.

Most cases of human infection are due to contact with infected poultry or surfaces that are contaminated with infected bird excretions: saliva, nasal secretions or feces.

In 2014 an H5N8 outbreak infected poultry on farms in Germany, the Netherlands and the United Kingdom.