WASHINGTON (Reuters) - The amount of oil being smuggled into Turkey from Syria was not enough for anyone to profit from it significantly, a senior U.S. State Department official said on Friday, rejecting claims by Russia that top Turkish officials were benefitting by smuggling oil from areas of Syria controlled by Islamic State.

An undated still image taken from a video made available by the Russian Defence Ministry in Moscow, Russia December 2, 2015, shows the Turkish-Syrian border crossing. REUTERS/Russian Defence Ministry/Handout via Reuters

The official, speaking on condition of anonymity, said the United States believed most of the oil smuggled from Islamic State-controlled areas was going into Syrian government-controlled territory and some into Iraq.

The Russian defense ministry claimed this week that it has proof Turkish President Tayyip Erdogan and his family were benefitting from smuggling oil from Islamic State-held territory. Erdogan denied the charges, saying he would stand down if such allegations were proven true.

“Our assessment is that there is not a lot of smuggling happening of any significant volume between ISIL controlled territories and Turkey,” the official said. “The volume itself of the oil being smuggled is extremely low and has decreased over time.”

The official estimated that to smuggle about 20,000 barrels of oil into Turkey per day it would take about 1,000 trucks, a number that had not been seen crossing the border.

“The economics don’t make sense for that to happen,” the official said. “The evidence doesn’t suggest that we would see thousands of trucks going through this territory and it would have to cross several different areas of control, and at every point have to pay fees.”

“I don’t see a lot of narrative in the argument that there is significant smuggling going,” the official added.

While the official acknowledged that some smuggling was occurring between the neighbors, he flatly rejected that it was of any significant volume that would be profitable.

“The oil is being consumed almost entirely inside areas of control of Syria and trading with the regime” of Syrian President Bashar al-Assad, the official said, adding, “ISIL is selling it into the economy.”

U.S., French and British jets have targeted Islamic-controlled oil fields in Syria as part of a campaign to cut the financial lifeline of the militant group. Hours after the British parliament agreed to join a coalition fighting the militant group, British bombers attacked six targets in the Omar oil fields in eastern Syria controlled by Islamic State.

U.S. officials have said that images posted by Russia of oil tankers crossing into Turkey from Syria were dated and were not of trucks crossing the border into Turkey.

“What I have not seen is imagery of the border crossing with trucks crossing the border, and that’s because I don’t believe that exists,” the official added.