Russian military cargo planes have taken supplies to Syria to set up a tent camp for more than 1,000 refugees, Russia's Defence Ministry says.

But the main Syrian opposition group blasted Moscow over its military presence in the country.

US President Barack Obama has expressed concern about Russia's increased military activity in Syria, particularly at an air base near the coastal city of Latakia. Russian Foreign Minister Sergey Lavrov has said that Russia is airlifting weapons to Syria, a long-time ally, and Russian troops are training the Syrian army on how to use them.

Moscow said today the humanitarian aid included materials for setting up a tent camp, including beds, mattresses, stoves, water cisterns and food.

The Syrian National Coalition condemned what it called "direct Russian military intervention," describing such a step as "hostile behaviour". The coalition's statement said the Russian intervention puts Moscow in a position that is "hostile to the Syrian people and turns its forces in Syria to occupation forces".

Russia has supported Syrian President Bashar Assad throughout the civil war by shielding him from UN sanctions and providing weapons. It also appears eager to send a broader message that Moscow remains loyal to its allies and strongly resents forceful change of regimes through foreign interference.

"The direct Russian military intervention will not lead to the regime's rescue, give it legitimacy or rehabilitate it," the coalition said in a statement. It added that the Russian intervention will "lead to more killing, destruction and displacement".

Meanwhile on Cyprus close to the Syrian coast, the government confirmed that Russian authorities have informed it of live-fire naval exercises to be conducted off Syria.

An official said such exercises are "routine" and occur every couple of months. It was not known when the exercises will take place.