Russian cargo planes have delivered Iranian weapons into Syria 20 times over the past 10 days, Fox News learned from western intelligence sources.

The flights are not registered and are in violation of an arms embargo on Iran imposed by two United Nations Security Council resolutions, the report notes.

Russian cargo planes have transported Iranian weapons to the Bashar al-Assad regime in Syria “twice a day over the past 10 days,” the unnamed sources told Fox News.

Earlier this month, the planes were spotted on the tarmac at Moscow’s airbase in Syria’s primary port city, Latakia.

Fox News learned that “the increased Russian transport of Iranian weapons is being coordinated by Qassem Soulimeini, the head of the Iranian Al-Quds force, as well as President Vladimir Putin and Russian Defense Minister Sergei Shoigu.”

Moreover, Iranian military personnel are being flown from Tehran into Latakia several times each day by Mahan Air, an Iranian civilian airline, points out Fox News.

“Tehran’s support has been crucial to Syrian President Bashar al-Assad’s survival. Besides significant financial aid to Assad, Iran has acknowledged that its Revolutionary Guard officers are on the ground in Syria in an advisory role,” adds the report. “There have been multiple Iranian officers and soldiers killed in fighting in Syria, though Tehran denies the presence of actual combat troops in the country.”

On Oct. 8, retired U.S. Gen. John Keane, who served as vice chief of staff of the Army and is now the chairman of the Institute for The Study of War (ISW), told the Senate Armed Services Committee that the Iranians are in Syria in far greater number than the Russian forces — 7,000 to 100-plus, respectively.

Retired U.S. Gen. John Allen, the outgoing special presidential envoy for the global coalition to counter the Islamic State (ISIS/ISIL), provided a much lower estimate for the number of Iranian troops in Syria when testifying before the Senate Foreign Relations Committee on Wednesday, saying less than 2,000 were there.

Earlier this month, an unnamed official with deep knowledge of operational details in Syria told the Associated Press (AP) that the Iranian Revolutionary Guards alone numbered around 1,500 at the time, adding that they began arriving after the Russian airstrikes in Syria began at the end of last month and “have accelerated recently.”

Iran has also deployed militia fighters to the front lines in Syria.

“Militias trained and led by the Russian Air Force, Syrian Arab Army, Lebanese [terrorist group] Hezbollah and Iranian Islamic Revolutionary Guard Corps (IRGC) have assembled a significant force in Syria,” reports Newsweek.

Iranian troops, allied Hezbollah fighters, Assad’s army, and the Russian Air Force have joined forces to seize key areas from rebels in Syria.

For the first time, Iranian officials have been invited to attend and participate in the next round of diplomatic talks in Vienna aimed at finding a solution to the Syrian conflict and formulating a “multilateral framework for a successful political transition” in the country.

Representatives from Russia, the United States, the United Kingdom, Egypt, Iraq, Qatar, Lebanon, Turkey, France, other members of the European Union, and Iran’s regional enemy Saudi Arabia, among other countries, are supposed to attend the talks. The Assad regime has not been invited to participate.