Turkey is currently at loggerheads with Russia after downing one of Moscow’s warplanes last month.

Iran said on Sunday it was its “duty” to mediate between Russia and Turkey as they trade accusations of buying oil from the Islamic State of Iraq and Syria.

“Iran has a duty to reduce tensions between Russia and Turkey and it’s not good to have another tension added to the existing ones in the region,” Ali Akbar Velayati, an advisor to Supreme Leader Ayatollah Ali Khamenei, was quoted as saying by the official Irna news agency.

Russia and Iran are major backers of Syrian President Bashar al-Assad’s regime.

Ankara is supporting rebels fighting Assad and earlier this year joined a U.S.-led coalition bombing ISIS in Syria.

Turkey is currently at loggerheads with Russia after downing one of Moscow’s warplanes on November 24.

Russia has accused Turkish President Recep Tayyip Erdogan and his family of involvement in the oil trade with ISIS — charges blasted as “slander” and “immoral” by the Turkish strongman.

Erdogan last week hit back, saying Turkey had “proof” that Moscow was buying oil from the miltiants in Syria.

Iranian media then picked up Russia’s claims prompting Erdogan to lash out at his Iranian counterpart.

Erdogan said he had warned President Hassan Rouhani in a telephone conversation that Iran would “pay a high price if it continues” to accuse Ankara.

Mohsen Rezaie, secretary of Iran’s Expediency Council, said Iranian military advisors on the ground in Iraq and Syria had images of IS oil trucks going to Turkey.

But Velayati later told state television the evidence Russia had released to support its claims meant “there is no need to publish more documents.”

“We should not take sides,” Velayati added.

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