"There are established procedures for these type of issues and those include summoning a representative of the violating nation to the foreign ministry," Klara Hook, press communicator at the Ministry for Foreign Affairs, told AFP.

"These procedures will be applied in this case as well," Hook added, declining to comment on whether the Russian ambassador had already been summoned or not.

While Russian incursions of the Nordic nation's airspace have happened in the past, Wednesday's event was treated with increased scrutiny given Russia's invasion of Ukraine.

"Against the background of the current situation we are taking the incident very seriously," Chief of Sweden's Air Force Carl-Johan Edstrom said in a statement Wednesday evening.

According to Sweden's air force the airspace "violation" was "brief" but Swedish Jas 39 Gripen jets were scrambled to document and photograph the two Su-24 and two Su-27 fighter jets.

Sweden's defence minister on Wednesday denounced the incursion as "completely unacceptable."

"This will lead to a clear diplomatic signal from the Swedish side," Peter Hultqvist said in a written statement to AFP.