Turkish President Recep Tayyip Erdogan on Thursday said Turkey does not buy any oil from Islamic State (ISIS), insisting that his country's fight against the jihadist group is "undisputed."
"Shame on you. Those who claim we buy oil from Daesh (IS) are obliged to prove it. If not, you are a slanderer," Erdogan said, lashing out at Russian charges after the downing of a warplane on the Syrian border.
Erdogan also said that Russia was Turkey's biggest energy supplier, followed by Iran.
Turkish F-16 jets shot down a Russian warplane on the Syrian border on Tuesday, prompting a tough response from Moscow, a major trade partner of Ankara.
Russian President Vladimir Putin has denounced the act as a "stab in the back" by "accomplices of terrorists."
The Turkish strongman denied Russian accusations that Ankara was collaborating with ISIS, saying his country's fight against the jihadists was undisputed.
"Our country's stance against Daesh has been clear since the very beginning," Erdogan said in a speech to local officials at his presidential palace in Ankara.
"There is no question mark here. Nobody has the right to dispute our country's fight against Daesh or to incriminate us."
Turkey has long supported Islamist rebels in Syria, and has been repeatedly accused of aiding jihadists including Al Qaeda's Nusra Front and ISIS.
AFP contributed to this report.