Russia's Defense Ministry on Saturday harshly criticized the US decision to send armored vehicles and combat troops into eastern Syria to protect oil fields, calling it "banditry".

Ministry spokesman Igor Konashenkov said that tank trucks guarded by US military servicemen and private military companies smuggle oil from fields in eastern Syria to other countries.

Russia's state Tass News Agency reported that oil was extracted with the use of the equipment supplied by leading Western firms bypassing all US sanctions.

Konashenkov said that the contract for transporting oil was executed by the US-controlled company Sadcub created at the so-called autonomous administration of eastern Syria.

"In the event of any attack on such a convoy, US special operations forces and combat aviation are immediately used to protect it.

"Revenues from smuggling Syrian oil arrive at numbered bank accounts of US private military companies and intelligence services through brokerage firms that interact with it," he said.

According to the Russian Defense Ministry, given that the cost of one barrel of oil smuggled from Syria is $38, the monthly revenue of that "private business" exceeds $30 million.

US Defense Secretary Mark Esper said Friday that Washington would send armored vehicles and troops to the Syrian oil fields to prevent them from falling into the hands of Islamic State militants.

Konashenkov said that maintaining a US military presence in eastern Syria was "international state banditry" motivated by a desire to protect oil smugglers and not by real security concerns.

"To secure such a continuous financial flow free from control and taxes, the top officials at the Pentagon and Langley will be willing to guard and protect oil wells in Syria from the imaginary 'hidden cells of the Islamic State' indefinitely," Konashenkov added.

Konashenkov said that space intelligence images show that Syrian oil was actively extracted and transported on a mass scale by tank trunks for processing outside Syria under the reliable protection of US troops both before and after the defeat of the Islamic State

"What Washington is doing now, that is, capturing and holding oil fields in eastern Syria under its control, is, putting it bluntly, international state-sponsored gangsterism," Konashenkov said.

Russia, which backs Syrian President Bashar al-Assad and has helped him turn the tide of a civil war, has long insisted that the US military presence in Syria is illegal, Reuters reported.

Bolstered position

Moscow has further bolstered its position in Syria following the US withdrawal from the northeast of the country, negotiating a deal last week with Turkey's President Recep Tayyip Erdogan that allows Turkey to remove the Kurdish People's Protection Units, or YPG, militia from within a 30-kilometer strip along the Syrian-Turkish border.

The Pentagon has not responded the Russian accusation, but the US Secretary of State Mike Pompeo held talks by phone with Russian Foreign Minister Sergey Lavrov on Saturday over the Syrian situation and US-Russian bilateral relations.

"From the Russian side, the necessity was emphasized of refraining from steps undermining the sovereignty and territorial integrity of that country," the Foreign Ministry said in a statement.

Russian President Vladimir Putin also discussed Syria in a phone conversation with his French counterpart Emmanuel Macron on Saturday.

The Kremlin said in a statement that during the conversation, the leaders agreed that the memorandum of understanding on the northern Syria situation signed by Russia and Turkey respects the interests of all the involved parties as well as promotes the restoration of sovereignty and territorial integrity of Syria.