Russia's defence ministry says one of its warships fired warning shots at a Turkish vessel in the Aegean Sea on Sunday to avoid a collision.
A ministry statement says the destroyer Smetlivy was unable to establish radio contact with the approaching Turkish ship, which also failed to respond to visual signals and flares.
When the vessel was 600 metres away, the destroyer fired with small arms and the Turkish vessel quickly changed course.
"The crew of the Russian patrol ship Smetlivy - which was located 22km from the Greek island of Lemnos in the northern part of the Aegean Sea - avoided collision with a Turkish seiner," the defence ministry told the AFP news agency.
Turkey's military attache in Moscow has been summoned by the ministry over the incident.
Tensions between Moscow and Ankara have been heightened since a Turkish jet downed a Russian bomber along the Syrian border last month, killing one of the two pilots.
Moscow has imposed a series of economic sanctions against Ankara after the incident, sparking the biggest crisis between the two countries since the Cold War.
Meanwhile, the Turkish army on Sunday banned staff from taking holidays in Russia, state-run media reported.
The prohibition, which applies to both personnel and military academy students, was described as a "precautionary measure after the Russian warplane, which violated [Turkey's] borders, was downed in accordance with the rules of engagement", Anadolu news agency said.
Army personnel are expected to behave in a way that is "worthy" of the Turkish military while on vacation, Anadolu added.