Moscow, Sep 20 : A nighttime drone attack by Ukraine killed four people and injured another in Russia's Samara region, Regional Governor Vyacheslav Fedorishchev said on Saturday.

"It is with deep sorrow that I report that four people were killed as a result of a night attack by enemy UAVs," Fedorishchev said on social media.

Another person was injured, and the regional government will provide the families of the victims with necessary assistance, including financial support, he added.

The Russian defence ministry said Saturday that air defence systems shot down 149 drones overnight, including 15 over the Samara region, Xinhua news agency reported.

Meanwhile, Russia said that a flight by three Russian MiG-31 fighter jets from Karelia to the Kaliningrad region adhered to international aviation rules and did not cross into the airspace of other countries.

In a statement published on its Telegram channel on Saturday, the Defence Ministry said that the redeployment flight on Friday was scheduled in advance and carried out under objective monitoring systems, which confirmed that no borders were violated.

The statement came after Estonia's Foreign Ministry summoned Russia's charge d'affaires on Friday to protest over what it claimed was an airspace violation by Russian aircraft.

The Estonian Foreign Ministry said in a statement that "the incursion took place over the Gulf of Finland, where three Russian Federation MIG-31 fighter aircraft entered Estonian airspace without permission and remained there for a total of 12 minutes."

Estonian Prime Minister Kristen Michal said Tallinn would seek NATO consultations under Article 4 in response to what she called Russia's provocations. Article 4 allows any NATO member to call for discussions when it perceives a threat to its territorial integrity or security.

/IANS