"Yes, we have started to reinforce our troops, and the operation will take us a week to 10 days to complete," the spokesman said on condition of anonymity.

The cabinet decided on Monday evening to dispatch army reinforcements to the border area in the north, after a series of frontier incidents in recent months, some of them deadly.

Syrian troops and armed men traded gunfire overnight in the border area and shells fell inside Lebanon, wounding civilians, the army said earlier.

The official Syrian news agency SANA confirmed the violence and said on Tuesday that troops foiled attempts by "armed terrorist groups" to infiltrate the border from Lebanon during the night.

The latest incident took place two days after clashes and blasts killed two people in the area.

France on Tuesday condemned Syrian shelling of areas of northern Lebanon and said it backed Lebanese plans to boost its military presence along the border.

"We support the decision of the Lebanese cabinet to strengthen the presence of the Lebanese armed forces at the border, to guarantee the security of Lebanon's territory and its people," French foreign ministry spokesman Bernard Valero said.

"France calls on Syria to strictly respect the sovereignty and territorial integrity of Lebanon, in conformity with United Nations resolutions," he added.

The Admiral Chabanenko and three landing craft have left their home port of Severomorsk in the Arctic Circle on their way to the Mediterranean where they will be joined by the Russian patrol ship Yaroslav Mudry as well as an assistance vessel, a military source told the agency.

The patrol ship Smetlivy from the Russian Black Sea Fleet's base in the Ukrainian port of Sevastopol is also on its way to Tartus, Interfax added.

"The programme of the voyage includes a call in the Syrian port of Tartus," the unnamed source told the news agency.

The source said the trip was taking place in line with the plans of military readiness of the Russian fleet. According to Interfax, the source insisted that the deployment "was not linked to the escalation of the situation in Syria."

"In Tartus the ships are going to top up on supplies of fuel, water and foodstuffs," the source said, adding that their deployment in the Mediterranean would last until the end of September.

The ministry of defence confirmed in a statement that a major deployment of Russian ships was planned in the Mediterranean Sea involving vessels from both the Northern and Black Sea Fleets, without giving further details.

The Tartus facility is a relic of Moscow's close ties with the regime of late Syrian president Hafez al-Assad in Soviet times and is Russia's only remaining military base outside the former Soviet Union.

However facilities for the Russian navy at Tartus are limited and the port is itself not deep enough to host large ships, which are forced to anchor outside.

The Russian military prefers to call the facility a "point of military-technical supply of the Russian Navy" rather than an actual base.

Russia has been bitterly criticised by the West for failing to cut military ties with Syria despite the conflict between the regime and opposition rebels that has claimed thousands of lives.

A separate Interfax report said that Russia was planning to deliver by sea to Syria a controversial cargo of three Mi-25 attack helicopters after a previous attempt ended when a British insurer dropped coverage.

"The cargo will be delivered to the customer by sea," a military source said, after previous reports said air delivery could be used.

The Alaed cargo vessel turned back when the United States publicly exposed the delivery and sparked international concern. The ship returned to the Arctic where it has been given a Russian flag.

The military source told the agency however that the cargo would not necessarily be delivered to Syria on the Alaed and another vessel could be used.