Turkey has accused Russia of again violating its airspace and warned it would "face consequences" if such infringements continue.
The foreign ministry said a Russian jet flew into its airspace on the border with Syria on Friday. Moscow described the claim as "baseless propaganda".
Tensions between the two countries have been high since November, when Turkey shot down a Russian jet.
Russia has been carrying out air strikes in Syria since September.
It has been targeting forces fighting the government of Syrian President Bashar al-Assad, its ally.
In a statement, the Turkish foreign ministry said a Russian SU-34 jet crossed into Turkish airspace at 11:46 local time on Friday, ignoring several warnings made in Russian and English.
It said the ministry had summoned the Russian ambassador in Ankara to "strongly protest at and condemn" the incident.
Turkish President Recep Tayyip Erdogan warned on Saturday that Russia would "have to face consequences if it keeps up such violations".
"Such irresponsible steps do not benefit either the Russian Federation, or Russia-NATO relations, or regional and global peace," he told reporters.
He said he had asked repeatedly for a meeting with his Russian counterpart, Vladimir Putin, without success.
NATO Secretary General Jens Stoltenberg said the violation had taken place, and urged Russia to "take all necessary measures" to ensure NATO airspace was not violated again.
"Previous incidents have shown how dangerous such behaviour is," his statement said.
The downing of the Russian warplane in November left relations between the two countries in tatters. Russia responded with economic sanctions that have hit Turkish exports and tourism revenues.
BBC / Reuters