A Mi-8 entered the Estonian airspace without permission at 11:55 a.m. on Thursday / Photo from wikipedia.org

A Mi-8 entered the Estonian airspace without permission at 11:55 a.m. on Thursday, military spokespeople in Tallinn said, Postimees wrote.

The helicopter stayed in the Estonian airspace for less than one minute. The craft's transponder was switched off and no flight plan had been presented to Estonia. There was no radio contact between the craft and the Estonian air navigation service during the incident.

The Police and Border Guard Board recorded the airspace violation near the northeastern tip of Lake Peispi both visually and by technical means. In  addition, border guards conducted additional surveillance of both the border lake and its shore but detected nothing out of the ordinary.

On Friday, the Estonian Foreign Ministry summoned the ambassador of Russia to deliver a protest.

This is the first case of violation of the Estonian airspace by a Russian aircraft this year. In 2015, aircraft of the Russian armed forces violated the Estonian airspace on three occasions. In 2014 the number of such incidents was eight and most of them happened near the Gulf of Finland island of Vaindloo.