Russian Foreign Minister Sergei Lavrov has warned that arming the Syrian opposition would be against international law.
Speaking to reporters in London on March 13 after talks with his British counterpart, William Hague, Lavrov also said he was concerned about the presence of Islamist radicals among the rebels.
His comments come a day after British Prime Minister David Cameron suggested London may veto an extension of a European Union arms embargo in Syria.
Russia has been one of Bashar al-Assad's biggest backers, shielding him from UN sanctions.
On the ground inside Syria, the EU announced a member of its delegation in the country had been killed in a rocket attack on a Damascus suburb.
Activists said government forces had intensified shelling of several outlying areas of Damascus believed to be rebel strongholds.
Based on reporting by dpa, AFP, and Reuters