NATO envoy for the South Caucasus James Appathurai described a border fence along Georgia's border with the republic as illegal. The fence was constructed last week by Russian border forces, state news agency RIA Novosti reports.
Georgian President Mikheil Saakashvili said from Washington last month he wanted U.S. support for Georgia's bid to join NATO, saying moving closer to the West was "crucial" for his country's survival.
Russia and Georgia went to war in 2008 over the breakaway territories of South Ossetia and Abkhazia. The Russian Foreign Ministry was quoted by RIA Novosti as saying NATO's frustrations were part of an effort to "stoke up the situation" along the border.
Russian President Vladimir Putin stirred controversy in April when he ordered snap military maneuvers in the Black Sea off the Georgian coast. He defended the drills as preparation for next year's Winter Olympics in the Black Sea resort city of Sochi.
The drill coincided with a decision by the government of Georgia to reject a draft non-aggression pact with Russia related to the breakaway republics.