Russia has accused Turkey of "creeping expansion" in Syria and say the Turkish military has established positions inside the war-torn country.
This is allegedly to prevent Kurdish militants from solidifying positions close to the Turkey – Syria border.
The remarks were made by Russian Foreign Minister Sergei Lavrov on Russian television news, Associated Press reported.
"Turkey has started to declare it has a sovereign right to create some safety zones on Syrian territory," Lavrov said in the TV interview.
"According to our information, they are digging in a few hundred meters from the border inside Syria."
He added: “It's a sort of creeping expansion."
The comments are the latest development in a tense relationship between Turkey and Russia.
In November 2015, Turkey shot down a Russian Su-24 military aircraft which it says violated its airspace.
Also in the interview, Mr Lavrov said that Russia would insist that Kurdish groups are represented at UN peace talks on ending the Syrian conflict.
Turkey has long objected to Kurdish militias, such as the Democratic Union Party (PYD) attending negotiations.
In a meeting with the British Foreign Secretary, Philip Hammond, this weekend, Turkish Foreign Minister Mevlut Cavusoglu reaffirmed Turkey’s stance on including Kurdish groups in peace talks.
“A terrorist organization should never be a reliable partner to defeat another terrorist organisation,” Mr Cavusoglu said, Anadolu Agency reported.
Mr Cavusoglu continued: “A terrorist organization, which is not radical Islamist should not be [considered] a better one than Daesh or Al Nusra."
“From time to time, Al Nusra is also fighting Daesh for their interest; therefore, we cannot legitimize any other terrorist organization just because they are fighting others on the ground."
"Therefore, the PYD should never be a reliable partner to defeat Daesh."
