Russia has upped its dispute with Turkey further by claiming to have evidence that proves President Recep Tayyip Erdogan and his family are benefiting from the illegal smuggling of oil from territory held by the Islamic State of Iraq and the Levant group (ISIL).
Moscow has repeatedly been making the claim that Ankara buys oil from ISIL since Turkish jets shot down a Russian warplane near the Syrian border last week - instantly sparking a diplomatic dispute that has seen both sides wage a war of words through the media.
Turkey has vehemently denied the ISIL oil claims, with Erdogan saying again on Wednesday that he would resign from his post if they could be proved.
Russian officials held a press briefing in Moscow on Wednesday at which they showed satellite images, that they said showed columns of tanker lorries loading with oil at installations controlled by ISIL in Syria and Iraq, and then crossing the border into neighbouring Turkey.
Russian Deputy Defence Minister Anatoly Antonov went further, implicating Erdogan's family in ISIL's oil supply chain.
"Turkey is the main consumer of the oil stolen from its rightful owners, Syria and Iraq. According to information we've received, the senior political leadership of the country - President Erdogan and his family - are involved in this criminal business," he said.
"Maybe I'm being too blunt, but one can only entrust control over this thieving business to one's closest associates."
"In the West, no one has asked questions about the fact that the Turkish president's son heads one of the biggest energy companies, or that his son-in-law has been appointed energy minister. What a marvellous family business!"
However, no specific evidence has been provided by Russian officials to prove their claims against the president, Al Jazeera's Rory Challands said in Moscow.
"Of course, this is not going to go down at all well in Ankara," he said.
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Speaking in the Qatari capital, Doha, Erdogan responded to the new claims on Wednesday by saying that no one had a right to "slander" Turkey.
"Nobody has the right to slander Turkey by saying Turkey is buying Daesh oil," he said, using an Arabic acronym for ISIL.
Other Turkish government officials described the claims as baseless, while a senior official from the ruling AK party founded by Erdogan, said they were part of a narrative being spun for a Russian domestic audience.
Erdogan, however, pointed out that he did not want relations between the two countries to get any worse.
Moscow and Ankara have been at loggerheads over the November 24 incident when Turkish jets shot down a Russian warplane - which Turkey claims illegally crossed into Turkish airspace.
Turkey has released a number of recordings which it claims prove that the warplane was warned repeatedly prior to being shot down.
Russia has hit back, slapping Turkey with a series of sanctions over the weekend - including bans on Turks' labour contract extensions, chartered flights from Russia to Turkey and tourism packages to Turkey.
Source: Al Jazeera and agencies