Turkey has accused Russia of a new violation of its airspace, warning Moscow against "irresponsible behaviour".
"A Su-34 plane belonging to the Russian Federation air force violated Turkish airspace at 11:46 (09:46 GMT) local time yesterday," the foreign ministry said in a statement.
The allegation comes just over two months after Turkey shot down a Russian warplane on the Syrian border on 24 November, saying it had violated Turkish airspace.
Ankara yesterday summoned the Russian ambassador to the foreign ministry to "strongly protest and condemn" the latest alleged violation, the ministry added, without specifying where it took place.
Ankara called on Russia to "act responsibly" and warned: "We stress once again that all the responsibility for any unwanted grave consequences as a result of any such irresponsible behaviour will belong entirely to the Russian Federation."
Moscow and Ankara are currently experiencing their worst relations since the end of the Cold War.
In addition to the 24 November incident which sparked a bitter diplomatic row, the two countries back opposing sides in Syria's civil war, with Russia the key supporter of the Damascus regime while Turkey argues that the ouster of Assad is essential to solving the Syrian crisis.