There were more than 104,000 new HIV diagnoses in Russia in 2017, taking total cases to more than 1.2million, but the number of infected people is believed to be higher.
The situation has concerned experts - who marked World Aids Day on Saturday - as Russia and Ukraine account for 75 per cent of all new infections in Europe amid a global decline.
Russia faces an escalating crisis with a rate - 71.1 new infections per 100,000 people - that is more than 10 times that of Western Europe (6.4 infections per 100,000 people).
Most new cases in the former Soviet Union in 2017 were from heterosexual sex as the disease spreads beyond high-risk groups, according to research by the World Health Organisation (WHO) and the European Centre for Disease Prevention and Control.
The increased rate of new diagnoses in the region since 2012 comes amid a global decline.
Masoud Dara, HIV specialist at the WHO, said it could be "an early indication of overspill in the general population".
He told the Thomson Reuters Foundation: "HIV starts off (in) key populations - meaning drug users, commercial sex workers and men having sex with men - but after that it (increases) exponentially ... if there is no more intervention."