All flights to Tartu were suspended between April 29 and May 31 while "an alternative approach solution that doesn't require a GPS signal can be put in place at Tartu Airport," the Finnish carrier said in a statement.

GPS interference can "prevent the aircraft from approaching and landing", Finnair said, adding the interference "is quite common in the area". Last week two Finnair flights headed for Tartu had to turn back to Helsinki due to GPS interference, it said.

Estonian Foreign Minister Margus Tsahkna on Monday told Estonian public broadcaster EER the GPS interference was the result of "completely deliberate actions", calling it a Russian "hybrid attack".

"Russia knows perfectly well that the interference caused by it is very dangerous to our aviation and goes against the international conventions, which Russia has also joined," Tsahkna told EER.

Baltic foreign ministers from Estonia, Latvia and Lithuania warned on Sunday in an interview with the Financial Times that widespread Russian GPS jamming increased the threat of an aviation accident, citing the case of the Finnish flights.

Finnair is the only airline operating international flights to the Estonian airport. "Flight safety is always our top priority, and as the approach to Tartu currently requires a GPS signal, we cannot fly there in the event of GPS interference," said Jari Paajanen, Finnair's director of operations.

The aim is to "build approach methods at Tartu Airport that enable a safe and smooth operation of flights without a GPS signal", Finnair said, adding that such alternative approach methods are used in most airports already.

GPS interference has increased since 2022, the airline said, with Finnair pilots reporting interference "especially near Kaliningrad, the Black Sea, the Caspian Sea and the Eastern Mediterranean".