Turkey says a Russian plane has again violated Turkey's airspace, two months after Turkey shot down a Russian warplane in a similar incident.
Turkish President Recep Tayyip Erdogan warned Russia on January 30 that it will "be forced to endure the consequences" if it continues to violate Turkey's airspace.
Russia, however, dismissed the claim as "baseless propaganda."
Erdogan's comments came hours after Turkey's Foreign Ministry said the Russian SU-34 jet entered Turkey's airspace on January 29 despite warnings in both Russian and English.
The ministry said in a statement that it has summoned the Russian ambassador to "strongly protest and condemn" the violation.
The ministry accused Russia of escalating tensions between the two countries.
"We are making a clear call to the Russian Federation not to violate Turkish airspace, which is also NATO airspace," the statement said.
NATO Secretary-General Jens Stoltenberg called on Russia "to act responsibly and to fully respect NATO airspace."
Stoltenberg said in a statement on January 30 that "Russia must take all necessary measures to ensure that such violations do not happen again."
The military alliance "stands in solidarity" with its NATO member Turkey, he added.
In Moscow, the Defense Ministry insisted that "there has not been a single violation of Turkish airspace by Russian Air Force planes in Syria."
"The Turkish declarations concerning the alleged violation of its airspace by a Russian Su-34 are baseless propaganda," ministry spokesman Igor Konashenkov told Russian news agencies on January 30.
Tensions have been high between Ankara and Moscow since Turkey's downing of the Russian Su-24 bomber near the border with Syria on November 24, saying it violated Turkish airspace for 17 seconds despite repeated warnings.
Russia insists the plane never entered Turkish airspace. One pilot and a Russian marine of the rescue party were killed in the incident.
Russia has since imposed economic sanctions on Turkey, hitting its tourism and exports.
Last September Russia began airstrikes in Syria against forces fighting troops loyal to Syria's embattled President Bashar al-Assad. Turkey is a vocal critic of Assad.