Russia's anti-drugs agency accused the Ukrainian secret service of attempting to hook Russian youths on drugs and promoting "anti-state" moods, Russian media reported.
Sergei Mosalev, deputy chief of the Federal Drug Control Service (FSKN) investigative department, claimed foreign agents were attempting to undermine the country ahead of September's parliamentary elections.
"According to our information, Ukraine's secret services, which are supervised by the West, are carrying out well-planned, anti-Russian activities, with the goal of increasing drug addiction among our youth, forming anti-state and anti-social moods," Mosalev was quoted by Interfax as saying.
Amid rising discontent about Russia's economy, the Kremlin seems concerned at the prospect of public ire being expressed at the ballot box, and has stepped up rhetoric against alleged western-backed 'fifth columnists' and agitators.
Russia and Ukraine have been at loggerheads since the 2014 Maidan Revolution, in which pro-Russian president Viktor Yanukovych was ousted after mass protests. The Minsk ceasefire agreement between pro-Russian militants in east Ukraine and government forces is on the verge of collapse, with fighting escalating in recent weeks.
Illegal drugs use is on the increase in Russia. Last year the FSKN said that three million Russians abused drugs on a daily basis and the country is responsible for one fifth of the global heroin consumption. Despite the country's currency crisis causing drug prices to increase, experts say that addicts are instead resorting to synthetic drugs.