Russia's Defence Ministry denied its aircraft violated Estonia's airspace, after Tallinn reported three fighter jets crossed into its territory on Friday without permission and remained there for 12 minutes.
The incident, described by Estonia's top diplomat as an "unprecedentedly brazen" incursion, happened just over a week after Nato planes downed Russian drones over Poland, heightening fears that Moscow's war on Ukraine could spill over.
In an online statement published early on Saturday, Moscow stressed its fighter jets had kept to neutral Baltic Sea waters more than three kilometres (1.8 miles) from Estonia's Vaindloo Island in the Gulf of Finland.
"On September 19, three MiG-31 fighter jets completed a scheduled flight from Karelia to an airfield in the Kaliningrad region," it said, referencing the Russian enclave sandwiched between Polish and Lithuanian territory.
"The flight was conducted in strict compliance with international airspace regulations and did not violate the borders of other states, as confirmed through objective monitoring," the statement said without providing details about the monitoring operation.
On Friday, Estonian officials said Tallinn had summoned a Russian diplomat to protest, and also moved "to start consultations among the allies" under Nato's Article 4, which states that parties would confer whenever the territorial integrity, political independence or security is threatened.