BEIRUT/UNITED NATIONS--Western and Arab countries responded with outrage on Sunday after Russia and China vetoed a U.N. Security Council resolution that would have backed an Arab plan urging Syrian President Bashar al-Assad to give up power.

U.S. Secretary of State Hillary Clinton called the veto a "travesty". The vote came a day after activists say Syrian forces bombarded a district of Homs, killing more than 200 people in the worst night of bloodshed of the 11-month uprising.

Russia said the resolution was biased and would have meant taking sides in a civil war. Syria is Moscow's rare ally in the Middle East, home to a Russian naval base and a customer for its arms. China's veto was widely seen as following Russia's lead.

Washington's U.N. ambassador Susan Rice said she was "disgusted" by Russia and China's vetoes, and "any further bloodshed that flows will be on their hands."

Britain's Foreign Minister William Hague said Moscow and Beijing had turned their backs on the Arab world. France's Alain Juppe said they "carried a terrible responsibility in the eyes of the world and Syrian people."

All 13 other members of the Security Council voted to back the resolution, which would have "fully supported" an Arab League plan under which Assad should cede powers to a deputy, withdraw troops from towns and begin a transition to democracy. The Western criticism was echoed in the Middle East, where Arab powers like Saudi Arabia and non-Arab Turkey have turned decisively against Assad in recent months.

"Unfortunately, yesterday in the U.N., the Cold War logic continues," said Turkish Foreign Minister Ahmet Davutoglu. "Russia and China did not vote based on the existing realities but more a reflexive attitude against the West."

Arab League head Nabil Elaraby said the body still intends to build support for its plan. The veto "does not negate that there is clear international support for the resolutions of the Arab League," he said in a statement seen by Reuters.

The Security Council's sole Arab member, Morocco, voiced "great regret and disappointment" at the veto. Ambassador Mohammed Loulichki and said the Arabs had no intention of abandoning their plan.

Burhan Ghalioun, head of the opposition umbrella Syrian National Council, called Moscow and Beijing's veto "a new license to kill from these two capitals for Bashar al-Assad and his criminal regime, which just yesterday killed 300 people."

The SNC said it held Moscow and Beijing "responsible for the escalating acts of killing and genocide."

Protesters stormed Russia's embassy in Libya's capital Tripoli on Sunday, climbing on the roof and tearing down the flag. Men held up a banner saying: "Libyan revolutionaries are ready to fight with their brothers in Syria."

Russia's U.N. envoy, Vitaly Churkin, accused the resolution's backers of "calling for regime change, pushing the opposition towards power and not stopping their provocations and feeding armed struggle."

"Some influential members of the international community, unfortunately including those sitting around this table, from the very beginning of the Syrian process have been undermining the opportunity for a political settlement," he said. Moscow is sending Foreign Minister Sergei Lavrov to Damascus on Tuesday.

Clinton had met Lavrov before Saturday's vote for what U.S. officials called "vigorous" talks. "What happened yesterday at the United Nations was a travesty," she said on Sunday. "Those countries that refused to support the Arab League plan bear full responsibility for protecting the brutal machine in Damascus."

She added: "Faced with a neutered Security Council, we have to redouble our efforts outside of the United Nations with those allies and partners who support the Syrian people's right to have a better future."