"We will do everything possible to prevent the accession of Ukraine and Georgia to NATO and to avoid the possible worsening of relations with the alliance, its leading member states and our neighbors," Sergei Lavrov said in an interview with the Moscow-based Ekho Moskvy radio.
Lavrov said Ukraine's and Georgia's possible admission is "the key irritant threatening to turn relations into a real problem with those NATO countries trying to force through this decision."
At a summit in Bucharest on Thursday, NATO members decided to postpone offering Georgia and Ukraine the chance to join the alliance's Membership Action Plan (MAP), but promised to review the decision in December. The ex-Soviet republics had received strong U.S. backing for their bids.
The minister said that prior to the Bucharest summit, the alliance's leading members affirmed that Ukraine and Georgia would decide for themselves whether to join NATO.
Lavrov, however, said after the summit that NATO members had indicated that Ukraine's and Georgia's admission would take place for sure which meant "interference in the countries' internal affairs."
"In Ukraine about 70% of the population are against joining NATO. If we take Georgia, then [the unrecognized republics of] Abkhazia and South Ossetia don't even want to hear about Georgia becoming a NATO member," Lavrov said.