The Georgian and Polish presidents have accused Russian troops of firing near a motorcade carrying them close to the breakaway republic of South Ossetia.
Both South Ossetian troops and Russian forces in the area denied involvement. No-one was injured in the incident.
President Mikhail Saakashvili and his Polish counterpart Lech Kaczynski were planning to visit victims of fighting between Georgia and Russia in August.
The area has seen much cross-border gunfire since a ceasefire was agreed.