MOSCOW: A Russian ship that tried to supply attack helicopters to Syria last month before being forced back was Sunday sighted sailing back home after unexpectedly starting a new voyage.

The privately-chartered Alaed had to return to Russia after its initial attempt to deliver the controversial cargo to President Bashar al-Assad's regime in June was exposed by the US State Department.

The 9,000-tonne private cargo was forced to turn back when its British insurer ended up pulling coverage.

The ship then docked in an Arctic port before setting sail again on Tuesday following pledges by Russian military officials to complete the delivery despite the anger it caused in the West.

The timing of the second voyage sparked alarm as it coincided with the deployment of a Russian flotilla to the Mediterranean that could have provided protection from any foreign attempt to block the ship.

The Russian arms export agency on Friday confirmed that the helicopters were aboard the Alaed when it set sail for the second time but refused further comment.

The MarineTraffic.com website that tracks global maritime activity showed the Alaed's radar signal coming in Sunday just north of Denmark following the ship's southern passage along the Norwegian coast.

The ship was shown to be sailing eastward to the Baltic Sea -- in line with suggestions from the owner that it would dock in Saint Petersburg after making a brief port call in the Kaliningrad exclave in the coming days.

Russian officials had earlier suggested that the shipment -- originally also carrying air defence systems that have not been mentioned in more recent reports -- may eventually be delivered to Syria by air.

The three Mi-25 helicopters were repaired in Kaliningrad and some analysts believe that they may be dropped off there by the Alaed before its goes on to Saint Petersburg to pick up new cargo.

Moscow has vowed to fulfill a helicopter repair contract it signed with its last Middle East ally in 2008 while promising not to supply any of its latest technology to Assad while the fighting in Syria continues.