President Recep Tayyip Erdogan has denied that Turkey bought oil from the Islamic State of Iraq and the Levant (ISIL) after Russia accused Ankara of turning a blind eye to oil smuggling by the group.
"Shame on you - those who claim we buy oil from Daesh [ISIL] are obliged to prove it. If not, you are a slanderer," Erdogan said, speaking to officials in the capital on Thursday.
Russian President Vladimir Putin on Thursday said there was "no doubt" that oil from "terrorist-controlled" territory in Syria was making its way across the border into Turkey.
The accusations came after Turkey shot down a Russian fighter jet on its southern border with Syria, bringing Ankara's relations with Moscow to their worst level in recent memory.
"We see from the sky where these vehicles [carrying oil] are going," Putin said after the incident. "They are going to Turkey day and night."
Erdogan shot back at Putin saying: "Daesh sells the oil they drill to [Syrian President Bashar] al-Assad. To Assad. Talk this over with Assad you support."
Erdogan also said Turkey was taking precautions to stop oil smuggling at its borders, a key source of revenue for ISIL.
The president added the places from where Turkey buys its oil and natural gas were well known, citing Russia and Iran as well as Azerbaijan and northern Iraq.
'Standing rules of engagement'
In an opinion piece published by Britain's Times newspaper on Friday, Prime Minister Ahmet Davutoglu said discussions were taking place after the downing of the fighter jet.
"While the measures to defend our territory will remain in place, Turkey will work with Russia and our allies to calm tensions," Davutoglu wrote.
"The downing of an unidentified jet in Turkish airspace was not - and is not - an act against a specific country. Turkey took action, based on standing rules of engagement, to protect the integrity of its sovereign territory."
The Turkish prime minister urged all sides not to be distracted "from the cause that unites us".
"The international community must not turn on itself. Otherwise, the only victors will be Daesh and the Syrian regime. This symbiotic relationship keeps both alive," he said.
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Turkish Foreign Minister Mevlut Cavusoglu also said Ankara did not need to apologise "on an occasion that we are right," adding he had already said "sorry" in a phone call with Russian counterpart Sergei Lavrov.
Earlier, Putin denounced the act as a "stab in the back" by "accomplices of terrorists".
But Erdogan denied Ankara was collaborating with ISIL.
"Our country's stance against Daesh has been clear since the very beginning," Erdogan said in his speech 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 and Russia stand on opposing sides of the four-year Syrian conflict, with Ankara pushing for the ouster of Assad by backing moderate opposition rebels.
Moscow is one of the few remaining allies of the Syrian government.
Russia further enraged Turkey with the launch of its air campaign in Syria in September, accusing Moscow of focusing its fire on moderate rebels rather than ISIL fighters.
"Those who carry out a military campaign with the pretext of fighting Daesh are targeting anti-regime opponents," Erdogan said.
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"You say you are fighting Daesh. Excuse me, but you are not fighting Daesh. You are killing our Turkmen kinsmen hand-in-hand with the regime in order to clear areas north of Latakia," he said, referring to the Syrian port city.
ISIL fighters have severely damaged Islam and the Muslims, he said, but added there was no difference between "an organisation's terror and state terror," referring to the Assad government.
Erdogan called Russia a "strategic partner" which he said required solidarity rather threats. "We are saddened by this," he said.
"There is no reason for us to target Russia with which we have multi-faceted and very strong ties, without any border violation," he noted, saying disagreements with Moscow over the Syrian crisis and Ankara's activating its military rules of engagement were two separate things.
"If the same incursion happens today, Turkey will be obliged to retaliate."
Erdogan also hit back at Putin's charges that Turkey's leaders were encouraging the Islamisation of the country.
"How dare you speak like that," said Erdogan. "Ninety-nine percent of Turkey is Muslim."