"The accession of Georgia to the current unreformed NATO structure would seriously affect Russia's political, military and economic interests, and would have a negative impact on the fragile situation in the Caucasus," the ministry said in a statement.
NATO has expanded to include many of Russia's former Communist-bloc allies in Eastern Europe and the former Soviet republics of Latvia, Lithuania and Estonia in the Baltic region. And a NATO ministerial meeting on the sidelines of the UN General Assembly session in New York has decided to step up a dialogue with Georgia with the aim of admitting the Caucasus state next year.
"Any kind of NATO expansion results in considerable changes in the security outlook," the statement said. "But the case with Georgia is of particular importance due to its geographical proximity to Russia, and because of its obvious complicity in Caucasian problems."
The ministry said the intensification of dialogue "means in practice giving Georgia a qualitatively new status in relation to NATO."
"It is obvious that Tbilisi considers this new format as a major step toward Georgia's accession to NATO," the ministry said. "Our [Russia's] negative attitude is obvious. The nature of new security risks and threats demands other forms of international cooperation than the expansion of military-political alliances formed during the Cold War."
The ministry also said past experience shows that, after joining NATO, some countries try to resolve their differences with Russia in the context of Russia-NATO relations.
"In regard to Georgia, we may expect a further escalation of existing problems, and we will have fewer chances to resolve them," the statement from the ministry said. "We have already explained all this to official Tbilisi. However, it looks as if its intention to act against Russia's interests has not changed."
Relations between the former Soviet states have been strained over the presence of Russian peacekeepers in conflict zones involving two self-proclaimed republics in Georgia and other issues, including a Russian ban on the import of Georgian mineral water and wine.
But the Russian Defense Minister Sergei Ivanov said earlier in the day that Georgia's possible accession to NATO will not threaten Russia's security.
"The number of questions asked about Georgia seems to give the impression that Georgia is the focus and priority of Russia's international policy," said Ivanov, who is also a deputy prime minister.
"NATO membership is an issue for Georgia, and Russia has nothing to do with it," he said.
But Ivanov reminded journalists that Russia would deploy two mountain brigades in the Caucasus near the border with Georgia. "Russian security will not be affected if Georgia joins NATO," he said.