Russia is facing the start of a flu epidemic, with most cases proved to be swine flu, the country's Research Institute of Influenza warned Friday.

"High growth rates of influenza and other acute respiratory viral diseases (ARVI), as well as a large number of viral diseases registered in towns and deaths resulting from influenza A(H1N1) pdm09 strain, apparently indicate the start of an epidemic," said a statement from the agency.

It said the nationwide morbidity rate of 60.6 per 10,000 of population was lower than the national baseline by 12.8 percent so far.

However the agency did not provide the number of deaths registered so far, while local media reported 15 registered fatalities in Russia's second largest city of St. Petersburg alone.

"We have information about 15 deaths, practically all of them confirmed of swine flu essentially complicated by pneumonia," Interfax news agency quoted Tatyana Zasukhina, deputy head of the Health Committee of St. Petersburg, as saying.

Russia's sanitary and epidemiological watchdog Rospotrebnadzor's St. Petersburg branch issued Friday an order declaring the epidemic in the city.

Since late 2015, several dozen cases of swine flu, some being fatal, were registered in 49 regions of Russia, including the westernmost Kaliningrad, as well as in some countries neighboring Russia.

A total of 21 cases of H1N1 influenza have been registered in Russia's Kamchatka territory as of Friday, while official data released Thursday showed seven cases recorded in Crimea peninsula and four in Kaliningrad.

Three people have reportedly died of swine flu in Russia's neighboring country Georgia since the start of the year.

Meanwhile, Ukrainian Health Ministry said Friday that as of last Thursday, an outbreak of flu in the country has claimed the lives of 72 people. The reason behind the high flu mortality rate is late medical treatment, according to the ministry.

Chief sanitary inspector at Rospotrebnadzor Anna Popova said Russian specialists were ready to counter a possible swine flu outbreak, with all necessary measures being taken already.

In an online statement, Popova said the flu and other ARVI epidemic threshold had been exceeded in 13 regions of the country by the end of the second week of January 2016.

She said monitoring showed that the share of swine flu strain in all ARVI cases rose from four percent by the end of December of 2015 to 42 percent.

Nevertheless, nearly 45 million out of 146 million Russians in the whole territory have been vaccinated against flu this year and not a single case of the disease have been registered among the vaccinated.

Russian Deputy Prime Minister Olga Golodets on Friday urged all Russians, especially those in high-risk groups, to be vaccinated.

Influenza A (H1N1) virus is the subtype of influenza A virus. In June 2009, the World Health Organization declared the new strain of swine-origin H1N1 as a pandemic.

This strain is often called swine flu by the public media. This novel virus has spread worldwide and caused about 17,000 deaths since the start of 2010.