MOSCOW: Syrian rebels have acquired portable surface-to-air missiles including U.S.-made Stingers, the Interfax news agency quoted Russia's senior general as saying on Wednesday.

Like Syrian President Bashar al-Assad, Russia has laid most of the blame for continuing violence on armed government foes it says are aided by encouragement and arms from abroad.

Russia's military has learned "that militants fighting Syrian government forces have portable missile launchers of various states, including American-made Stingers," Interfax quoted general staff chief Nikolai Makarov as saying.

"Who supplied them must still be determined," he said.

NBC News reported in late July that the rebel Free Syrian Army had obtained nearly two dozen shoulder-fired surface-to-air missiles, also known as MANPADs. A political adviser to the Free Syrian Army denied it.

In contrast to the Libya crisis, the West has shown little appetite to arm the Syrian rebels, worried that weapons would fall into the hands of Islamic militants.

Russia sold the government in Syria $1 billion worth of weapons last year and has made clear it would oppose an arms embargo in the U.N. Security Council because of what it says are concerns rebels fighting Assad's government would get weapons illegally anyway.

The West has criticised Russia for vetoing, along with China, three Security Council resolutions aimed at putting pressure on Assad to end a 19-month conflict. Moscow says it opposes foreign interference in Syria's affairs.

Activists say the conflict has killed more than 30,000 people since protests against Assad erupted in March 2011.