LONDON — The United States has been working with NATO allies to track a Russian weapons ship to Syria.

Western diplomatic sources said Britain and the United States were coordinating patrols of the North Sea for a Russian vessel that contained attack helicopters for the regime of President Bashar Assad.

The sources said the Russian ship was transporting Mi-24 helicopters overhauled by Russia’s state-owned arms agency Rosoboronexport. “At this point, the mission is to track the weapons ship not intercept it,” a diplomatic source said.

At first, the administration of President Barack Obama said the Kremlin had ordered a shipment of new attack helicopters to Damascus. Later, Secretary of State Hillary Clinton clarified that the helicopters were Syrian Army platforms overhauled in Russia.

Officials did not say how many Mi-24s were suspected aboard the Russian ship. But they said Assad reached an agreement for the upgrade of 36 Mi-24s acquired by Damascus nearly 20 years ago.

For its part, Russia has denied reports of a weapons ship bound for Syria. The latest reports in the Western media identified the Russian Navy ship as Nikolai Filchenkov, said to have left the Crimea for the Syrian port of Tartous. “The ship is in the state of instant readiness for departure like all of the fleet’s warships,” a Russian Navy source told the RIA-Novosti agency on June 17. “There are no marines aboard the ship, and there were no commands for a voyage towards Syria. The crews are engaged in day-to-day activities.”

At the same time, the Russian Navy has been preparing to send several warships to Syria. On June 15, an unidentified member of the Russian General Staff told the Itar-Tass news agency that the Black Sea Fleet has been assigned to protect Russian interests in and around Syria.

“The Mediterranean Sea is a zone of the Black Sea Fleet responsibility,” the Russian general said. “Therefore, warships may go there in case it is necessary to protect the Russian logistics base in Tartous, Syria. Several warships of the Russian Black Sea Fleet, including large landing ships with marines aboard, are fully prepared to go on the voyage.”

Earlier, human rights groups said a Russian cargo vessel, Professor Katzman, brought weapons to Tartous on May 26. Washington has asserted that Moscow was sending weapons and ammunition to Assad but did not refer to the cargo vessel.

“It was a general cargo of non-military purpose featuring electrical equipment and repair parts — rotor blades — in containers and wooden crates,” Universal Cargo Logistics Holding, which owns Professor Katzman, said on June 16.

Russian leaders said the Kremlin has approved continued delivery of combat platforms for Assad. They said the platforms — believed to include the MiG-29 fighter-jet, trainer jets and air defense batteries — were ordered by Damascus as early as 2007. (Copyright © 2012 East West Services, Inc. 06/18/12)