Turkish President Recep Tayyip Erdogan says Ankara has proof that Russia was involved in the illegal oil trade with the Islamic State (IS) extremist group in Syria.
"We have the proof in our hands. We will reveal it to the world," Erdogan said in a televised address on December 3 in Ankara. He did not elaborate.
Erdogan described as "immoral" Russian allegations made a day earlier that Erdogan's family was importing oil from IS militants.
The Russian Defense Ministry on December 2 accused Erdogan and his family of involvement in the illegal oil trade with IS after Ankara's downing of one of Moscow's warplanes last week. The deadly incident plunged relations between the two countries to a crisis level.
Erdogan repeated his previous vow to resign if the allegations made by Moscow were proved to be true.