Estonia said it detected the incursion on Tuesday while it was inspecting a tanker from the so-called "shadow fleet" of ships that experts believe Russia is using to dodge sanctions.

"Russia responded dangerously aggressively by accompanying the shadow fleet tanker with a fighter jet, which violated Estonian airspace," Estonian Foreign Minister Margus Tsahkna told a NATO meeting in Turkey.

"This incident is yet another example showing that Russia poses a serious threat not only through its war in Ukraine but also to the NATO alliance as a whole," he added on X.

Since Russia's invasion of Ukraine in 2022, Estonia -- a member of the European Union and NATO -- has been a staunch ally of Kyiv.

It has also approved measures to boost maritime security, after incidents targeting vital infrastructure on the Baltic seafloor.

Last year the Estlink 2 electricity cable and four telecom cables linking Finland and Estonia were damaged.

Investigators suspect the cables were hit by the anchor of the Eagle S, a Cook Island-flagged oil tanker believed to be part of the "shadow fleet".

In the latest incident, Estonia was inspecting "the unflagged and uninsured Argent/Jaguar (tanker), which is sanctioned by the United Kingdom", when the Russian aircraft violated Estonia's airspace, Tsahkna said.

He said NATO fighter jets had been scrambled to "inspect and check the Russian fighter".