Prime Minister David Cameron has chaired a meeting of the National Security Council (NSC) to discuss the deteriorating situation in Syria.
The meeting came as European Union states began work on a new round of sanctions against the Middle Eastern country, expected to be agreed on February 27, which could include a freeze on Syria's central bank assets and a ban on trade in precious metals.
Ahead of the NSC meeting, Foreign Secretary William Hague briefed Cabinet on developments following Russia and China's veto of a United Nations resolution designed to end President Bashar Assad's bloody crackdown on dissent.
Violence has escalated since the UN process hit the buffers on Saturday, with regime forces reported to be using tanks and machine guns in an effort to seize control of rebel strongholds in the city of Homs.
Russian foreign minister Sergei Lavrov is visiting Syrian capital Damascus in what Moscow said is part of an effort to "seek the swiftest stabilisation of the situation in Syria on the basis of the swiftest implementation of democratic reforms whose time has come".
He was given a warm welcome by thousands of flag-waving Assad loyalists who thronged the streets to express their gratitude for Moscow's supportive stance.
According to Russian news agency RIA, Mr Lavrov told the Syrian president: "Every leader of every country must be aware of his share of responsibility. You are aware of yours.
"It is in our interests for Arab peoples to live in peace and agreement."
On Monday, Mr Hague condemned the Russian and Chinese vetoes as "a betrayal of the Syrian people" and pledged that the UK would seek other means of putting pressure on the Assad regime, including the creation of an international Friends of Syria group.
France and Italy have recalled their ambassadors from Syria for consultations, a day after Britain took the same step and the US closed down its embassy in Damascus.