MOSCOW/ANKARA (Reuters) - Iranian Major General Qassem Soleimani has flouted an international travel ban and flown to Moscow for talks with Russia’s military and political leadership on Syria and deliveries of Russian missiles, sources said on Friday.

Iranian Revolutionary Guard Commander Qassem Soleimani (L) stands at the frontline during offensive operations against Islamic State militants in the town of Tal Ksaiba in Salahuddin province March 8, 2015. Picture taken March 8, 2015. REUTERS/Stringer

The main purpose of his visit was to discuss new delivery routes for shipments of Russian S-300 surface-to-air missile systems, sources said. Several sources also said Soleimani wanted to talk about how Russia and Iran could help the Syrian government take back full control of the city of Aleppo.

“General Soleimani traveled to Moscow last night to discuss issues including the delivery of S-300s and further military cooperation,” a senior Iranian security official told Reuters.

Soleimani met Russian President Vladimir Putin and Defence Minister Sergei Shoigu on Friday, one source said. A Kremlin spokesman said a meeting with Soleimani was not on Putin’s schedule.

Asked about Soleimani’s visit, the Iranian embassy in Moscow said it had no information about it.

U.S. State Department spokesman John Kirby said Secretary of State John Kerry raised concerns about reports of Soleimani going to Russia in a phone call with Russian Foreign Minister Sergei Lavrov on Friday, but added that Washington was not in a position to confirm the visit.

Kirby said U.N. sanctions on remained in effect, “so such travel, if true, would be a violation of U.N. Security Council resolutions, and we believe, then, a serious matter of concern to both the U.N. and the United States.”

A U.S. official, who spoke on condition of anonymity, said the United States would continue to insist that Russia and other countries comply with U.N. obligations “and prevent the international travel of Soleimani.”

“We also intend to continue to raise the issue in New York,”

the official said, referring to the United Nations.

Soleimani’s visit is likely to be seen as a sign that the tactical alliance of Russia and Iran over Syria remains strong despite some reported differences over battlefield strategy.

“Soleimani’s most likely meetings would be with (Russian) military leaders – Defence Minister Sergei Shoigu, among others, although the possibility of meeting with President Putin cannot be ruled out,” said Yuri Lyamin, a Russian security analyst who follows Russian-Iranian military developments.

Iranian media reported on Monday that Russia had delivered the first part of the S-300 missile system, providing technology that was blocked before Tehran signed a deal with world powers on its nuclear program.

Soleimani, the commander of foreign operations for Iran’s elite Revolutionary Guards, flew to Moscow in July last year to help Russia plan its military intervention in Syria and forge an Iranian-Russian alliance to support Syria’s President Bashar al-Assad.

He helped reactivate the stalled S-300 deal, which Russia had put on ice in 2010 under pressure from the West.

Russia, despite withdrawing some of its fast jets, still maintains a significant military presence in Syria, providing air support, advice and training to the Syrian army.

A senior regional source told Reuters last year that Russia’s military intervention in Syria was set out in an agreement between Moscow and Tehran that said Russian air strikes would support ground operations by Iranian, Syrian and Lebanese Hezbollah forces.

Iran has committed troops to help prop up the Syrian army, sometimes sustaining heavy losses, and Soleimani has been reported to be spending time in Syria, where he is thought to have helped coordinate operations.

He remains subject to an international travel ban by the U.N. Security Council. Washington has also designated the Quds Force, the unit of the Revolutionary Guards that Soleimani leads, as a supporter of terrorism.

The U.N. ban remains in place despite implementation of a nuclear deal between Iran and world powers that triggered sanctions relief for Tehran.