MOSCOW/BEIRUT - Both rebels and forces loyal to President Bashar al-Assad are intensifying violence in Syria and striving for military gains rather than peaceful transition, the chief UN monitor in Syria said on Friday. Major-General Robert Mood's comments came as Russia further dug its feet in against Western pressure to topple Assad, insisting it would not discuss a post-Assad Syria. "Violence over the past 10 days has been intensified, again willingly by both parties, with losses on both sides and at significant risk to our observers," Mood said in Damascus. "There appears to be a lack of willingness to see a peaceful transition. Instead there is a push towards advancing military positions." In Moscow, Russian Foreign Minister Sergei Lavrov said discussions regarding a political transformation in Syria after Assad "are not being held and cannot be held, because to decide for the Syrian people contradicts our position completely". "We do not get involved in overthrowing regimes - neither through approval of unilateral actions by the UN Security Council nor by participation in any political plots," he said. His comments were a response to a remark by US State Department spokeswoman Victoria Nuland suggesting Washington and Moscow were discussing a post-Assad strategy in Syria. Russia's Foreign Ministry also rebutted accusations by U.S. Secretary of State Hilary Clinton that Russia was sending attack helicopters to Syria. It said Moscow had made no new deliveries, but had at some point carried out "previously planned repairs of (helicopters), which were delivered to Syria many years ago". World powers are deeply divided over Syria, with Russia and China - both permanent members of the U.N. Security Council with veto power - blocking efforts by Western powers to condemn Assad or call for his removal after 15 months of bloodshed. Violence has surged in recent weeks after government forces and allied militia launched offensives to regain territories controlled by the opposition and rebels abandoned a ceasefire negotiated by international envoy Kofi Annan.