The son of Turkish President Tayyip Erdogan has denied Russian allegations that he and his family were profiting from the illegal smuggling of oil from Islamic State-held territory in Syria and Iraq.

Russia's defense ministry said last week it had proof that the Erdogan family was benefiting from this trade. Turkey has already dismissed the accusations and the president's son Bilal added his voice to the many denials.

"We build offices in Istanbul ... We do not do business in the Mediterranean, in Syria or Iraq," he was quoted as saying in Corriere della Sera newspaper, talking about his own corporate concerns, which have been called into question by Russian media.

"ISIS is an enemy of my country. ISIS is a disgrace. It puts my religion in a bad light. They don't represent Islam and I do not consider them to be Muslims," he said, referring to Islamic State by one of its various acronyms.

One of the four children of President Erdogan, Bilal has shipping and maritime assets and controls several oil tankers through his company and partnerships in other firms.

However, he denied he had any operational shipping activities, saying his company had a contract to build "river tankers" for a Russian client, but that it did not operate the ships itself. He also denied that his brother Burak might have transported oil from lands controlled by Islamic State.

"He has a cargo ship, but it cannot be used as a tanker."

Instead, he said that Syrian President Bashar al-Assad was profiting from the sale of Islamic State oil. "If you follow ISIS oil, you will find Assad."

Damascus has previously accused the Turkish government, which is hostile to Assad, of allowing Islamic State insurgents to smuggle contraband out of northern Syria.

Relations between Turkey and Russia have chilled sharply after Turkey last month shot down a Russian warplane that it said had crossed into its air space from Syria.

"What happened concerning the Russian jet was unpleasant, but we have to concentrate on the real problems: ISIS and the future of Syria," Bilal Erdogan said.

Russian media reports suggested that Bilal was directly involved in oil trade with Islamic State and that Turkey downed the Russian jet to protect this oil smuggling business.

Bilal came to Italy earlier this year with his wife and family to finish doctorate studies in the city of Bologna. Critics accused him of fleeing Turkey in the wake of previous graft scandals. He denied any wrongdoing and said he was in Italy to concentrate on his studies.