Turkey says a Russian jet has violated its airspace and it has summoned the Russian ambassador to Ankara.
The foreign ministry said a Russian SU-34 jet violated Turkish airspace on Friday despite warnings in Russian and English.
Tensions have been high between Ankara and Moscow since Turkey shot down a Russian plane which violated its airspace near Syria in November.
The two have traded barbs and introduced retaliatory measures.
"A Su-34 plane belonging to the Russian Federation air force violated Turkish airspace at 11:46 local time yesterday (Friday)," the foreign ministry said.
Its statement went on to say that the Russian ambassador had been summoned to the foreign ministry to "strongly protest and condemn" the violation.
Russia began air strikes in Syria against forces fighting troops loyal to Syrian President Bashar al-Assad last September.
Turkey, a vocal opponent of President Assad, has long complained of Russian jets flying into Turkish airspace while carrying out its operations along the Syrian border - something Moscow denies.
But tensions escalated after two Turkish F-16s shot down a Russian SU-24 on 24 November.
Turkey complained that the plane intruded into its airspace and ignored repeated warnings to leave; Russia insisted the jet was over Syrian territory when it was hit, had never violated Turkish airspace and did not receive any warnings.
