Russia's defense ministry on Saturday accused the United States of turning a blind eye to the trafficking of oil into Turkey from Syrian areas under Islamic State control, after Washington called the amounts involved insignificant.

"When US officials say they don't see how the terrorists' oil is smuggled to Turkey, ... it smells badly of a desire to cover up these acts," the ministry said on its Facebook page.

"The declarations of the Pentagon and the State Department seem like a theater of the absurd," the statement added, suggesting that Washington "watch the videos taken by its (own) drones which have recently been three times as numerous over the Turkey-Syria border and above the oil zones".