Russia's President Vladimir Putin has resisted diplomatic pressure from Western nations to support tougher action against Syria's government.
Putin, an ally of Syria, called for more time to be given to the peace plan of envoy Kofi Annan.
The US and UK have called on Moscow to strengthen its condemnation of the Syrian regime since last week's massacre in Houla, where 108 died.
Earlier, Moscow opposed a UN Human Rights Council resolution on Syria.
In an emergency session yesterday, the council condemned Syria over the Houla massacre and called for an investigation.
But Russia voted against the US-backed resolution, arguing that it was "unbalanced".
Meanwhile, a US government website published satellite images apparently showing a mass grave in the Houla area.