Turkish President Recep Tayyip Erdogan has accused Russia of slander for its allegations that Turkey and Erdogan's family are buying oil from Islamic State (IS) militants.
Erdogan said during a speech at Qatar University on December 2 that "no one has the right to engage in slander against Turkey as to suggest that Turkey is buying oil from Daesh (IS)."
The Turkish leader's comments came hours after the Russian Defense Ministry claimed Erdogan and his family are involved in the illegal oil trade with IS.
At a briefing in Moscow on December 2, Russian Defense Ministry officials said the ministry knows of three routes by which Islamic State oil is directed to Turkey.
Russian Deputy Defense Minister Anatoly Antonov said "the top political leadership of the country, President Erdogan and his family, is involved in this criminal business."
Antonov said Erdogan's son heads a leading Turkish energy company and that his son-in-law has been named Turkey's energy minister.
"What a marvelous family business!" said Antonov sarcastically. "Obviously no one but the closest people could be entrusted to control such things [as oil bought from IS]."
Antonov offered no evidence of involvement by Erdogan or any of his family members in oil trade with IS.
Erdogan said in Qatar that "those who make such claims are obliged to prove them. If they do, I would not remain on the presidential seat for one minute. But those who make the claim must also give up their seat if they can't prove it."
U.S. Secretary of State John Kerry said Turkey is committed to sealing its border along areas in Syria that are controlled by Islamic State. He stressed on December 2 that Ankara has a vested interest in severing smuggling routes used by the extremist group.
According to Iraqi intelligence and U.S. officials, IS earns up to $50 million a month from sellling crude from oil fields under its control in Iraq and Syria.
Relations between Russia and Turkey have plunged since November 24 when a Russian warplane was downed by a Turkish F-16 near the border with Syria, killing one of the pilots.
Russian President Vladimir Putin, who has signed a decree imposing economic sanctions on Ankara over the incident, has said Turkey shot down the jet because it wanted to protect supplies of oil from Islamic State militants.
Turkish Prime Minister Ahmet Davutoglu said on December 1 that Russia was using these "unfounded" claims to "cover up" its violation of Turkey's airspace when the jet was shot down.
Erdogan said he is disappointed that Russia has escalated the situation by imposing economic and other sanctions on Turkey.
He said he doesn't wan't bilateral relations between the two countries to deteriorate further and he said "adding fuel to the flames is to no one's benefit."
With reporting by Interfax and Reuters