Vilnius, Oct 24 : Lithuanian President Gitanas Nauseda has said that Russian planes violated the airspace of NATO member Lithuania.

He claimed on Thursday night that the aircraft -- a fighter jet and transport plane -- came from the Kaliningrad region in the southwest.

"This is cruel violation of international law and territorial sovereignty of Lithuania, and we have to react to this," Nauseda said in a video posted on X.

Russia has, however, denied that its military planes violated Lithuanian airspace.

The Russian Defence Ministry has said that Su-30 fighter jets conducted scheduled training in the Kaliningrad region and did not deviate from their flight routes.

"The flights were carried out in strict accordance with the Rules for the Use of Airspace over the Territory of the Russian Federation," the Ministry said.

Lithuania's military has said the planes were possibly conducting refuelling exercises when they entered the airspace for about 700 metres and departed after about 18 seconds.

Two Spanish Air Force fighter jets, which are performing a NATO air policing mission, were scrambled to the site and are currently conducting air patrols, Lithuania's military said in a statement.

Lithuania's Foreign Ministry later said that it summoned the Russian Charge d'Affaires to protest the alleged violation.

"Once again, it confirms the importance of strengthening European air defence readiness," President Nauseda wrote on X.

Last month, NATO said it intercepted three Russian jets that violated Estonia's airspace.

The Russian Defence Ministry at the time denied the claim, insisting its flights were conducted "in strict accordance with international rules".

The Baltic nations have grown increasingly concerned over Russia's actions amid its ongoing war in Ukraine.

A series of recent drone incidents and airspace violations by Russian warplanes has fueled fears that President Vladimir Putin may be testing NATO's defensive response.

Some European leaders have accused Moscow of engaging in hybrid warfare, though the Kremlin has denied any such activities.

Lithuanian Prime Minister Inga Ruginiene also condemned the violation, describing it as another act of Russian intimidation.

"This incident once again shows that Russia is behaving like a terrorist state, disregarding international law and the security of neighbouring countries," Ruginiene wrote on Facebook, adding that Lithuania remains secure through its NATO alliance.

Meanwhile, tensions between the US and Russia continue to simmer as the war in Ukraine drags on.

US President Donald Trump has grown increasingly frustrated with his Russian counterpart, Vladimir Putin, as his efforts to end the conflict stall.

On Tuesday, Russian drones and missiles struck targets across Ukraine, killing at least six people, including a woman and her two young daughters.

"Hopefully, he'll become reasonable," Trump said of Putin during remarks at the White House on Wednesday alongside NATO Chief Mark Rutte, just hours after the US announced renewed sanctions on Russian oil aimed at pressuring Moscow.

/IANS