Turkey's president has warned Moscow it will face "consequences" after Ankara reported a Russian jet had entered Turkish territory. Russia has dismissed the claims as "baseless propaganda."
Turkish President Recep Tayyip Erdogan on Saturday accused Russia of taking "irresponsible steps" which threatened world peace.
"Russia will have to face consequences if it keeps on with such violations against Turkey's sovereignty rights," Erdogan told reporters in Istanbul.
"Such irresponsible steps do not benefit either the Russian Federation, or Russia-NATO relations, or regional and global peace," he said. "On the contrary they are detrimental."
Erdogan's comments came hours after Turkey announced a Russian jet had violated its airspace, despite several warnings sent by Turkish radar units in English and Russian.
"A Su-34 plane belonging to the Russian Federation air force violated Turkish airspace at 11:46 local time yesterday (Friday)," a Foreign Ministry statement said, without specifying where the infringement took place. The ministry also said the Russian ambassador had been summoned to "strongly protest" the violation.
Russian Defense Ministry spokesman Igor Konashenkov responded to the claims later on Saturday, saying that no violation of Turkish airspace had taken place.
"The Turkish declarations concerning the alleged violation of its airspace by a Russian Su-34 are baseless propaganda," he told Russian news agencies.
Meanwhile, NATO head Jens Stoltenberg urged Russia to "fully respect" alliance airspace.
"Russia must take all necessary measures to ensure that such violations do not happen again," he said in a statement, adding that the Western military alliance "stands in solidarity" with its NATO member Turkey.
Breakdown in relations
The alleged violation comes two months after Turkey shot down a Russian warplane near the border with Syria, killing a pilot. Ankara claimed the Su-24 bomber entered its airspace after flying too close to the Syrian-Turkish border, a charge rejected by Moscow.
The incident sparked the biggest crisis in bilateral relations since the end of the Cold War, with Russia introducing retaliatory economic measures and a more aggressive military stance against Turkey.
The two countries are also at odds over the conflict in Syria. While Russia is a key ally of President Bashar Assad and has launched airstrikes against his opponents, Turkey argues his ouster is crucial to ending the five-year Syrian civil war.
Erdogan said Saturday he wanted to meet with his Russian counterpart Vladimir Putin to discuss the latest incident. The two leaders have not met since the November jet downing.