The Estonian military says Russian aircraft violated Estonian airspace over the Baltic Sea, the fourth such violation by Russia this year.
The military said in a statement on September 6 that a Russian Antonov An-72 transport plane was in Estonian airspace without permission for about 90 seconds near the Baltic Sea's Vaindloo Island.
It said the Russian plane was not in contact with Estonian air-traffic controllers and had flown some 2.2 kilometers inside Estonian airspace.
Russian Defense Ministry spokesman Major General Igor Konashenkov told journalists on September 6 that no Russian planes "violated Estonia's airspace in the vicinity of Vaindloo Island."
He claimed that no Russian An-72s flew on September 6 in the area cited by Estonian officials.
The Russian Embassy in Estonia said its ambassador had been handed a protest note by Tallinn officials.
Several NATO countries have reported airspace violations by Russian aircraft this year.
Turkey shot down a Russian warplane late last year that it said was violating its airspace, something Turkish military officials said had happened several times and that Moscow had been warned about.