RUSSIA and China on Thursday vetoed a Western-backed United Nations Security Council resolution that threatened Syrian authorities with sanctions if they did not stop using heavy weapons against an uprising and withdraw troops from towns and cities.

It is the third time that Russia, a key ally of the Syrian government, and China have used their veto power to block Security Council resolutions designed to put pressure on Syrian President Bashar al-Assad and halt the violence in the 16-month conflict that has killed thousands of people.

The vetoed resolution, which would have extended a UN observer mission in Syria for 45 days, received 11 votes in favour, with two abstentions.

The 15-member council still has time to negotiate another resolution on the fate of the unarmed mission before its initial 90-day mandate expires at 4am GMT on Friday.

Britain, France, Germany and the US proposed in the vetoed resolution that international envoy Kofi Annan's six-point peace plan be placed under Chapter 7 of the UN Charter, which allows the council to authorise actions ranging from diplomatic and economic sanctions to military intervention.

Western council members have said they are talking about a threat of sanctions on Syria, not military intervention. Their vetoed resolution had contained a specific threat of sanctions if Syrian authorities did not stop using heavy weapons and withdraw troops from towns and cities within 10 days.

But Russia made it clear days before the vote that it would block any resolution on Syria under Chapter 7, with Russian Foreign Minister Sergei Lavrov describing the threat of sanctions against Syria as "blackmail".

Russia has also put forward a resolution to extend the UN mission for 90 days, but it does not contain a threat of sanctions. The Security Council initially approved the deployment of the UN observer mission to monitor a failed April 12 ceasefire under Mr Annan's peace plan.

If the mission is renewed, UN chief Ban Ki-moon has recommended shifting the emphasis of the work of the observer mission from the 300 unarmed military observers to civilian staff focusing on a political solution and issues including human rights.

The mission suspended most of its monitoring activity on June 16 due to increased risk from rising violence.

SOUTH AFRICA 'DEPLORES' VIOLENCE

Meanwhile, the South African government on Thursday added its voice to the growing alarm over the conflict in Syria.

"South Africa deplores the continuing violence in Syria, which is spinning out of control," said Deputy Minister of International Relations and Co-operation Ebrahim Ebrahim.

"Our highest priority is to stop the killing and end the suffering of innocent civilians," he said.

South Africa has called for an immediate end to the violence and for talks to reach a Syria-led transition reflecting the will of the Syrians.

"There is no military solution to the dispute. It is for this reason that South Africa strongly supports the tireless efforts of Mr Annan," said Mr Ebrahim.

He said the suicide bomb attack in the Syrian capital, Damascus, on Wednesday, which killed senior government officials including Defence Minister Daoud Rajha, and "the many horrific massacres" of the past few weeks showed there were two sides to the conflict.

Mr al-Assad's brother-in-law, Assef Shawkat, and Gen Hassan Turkmani, head of the government's crisis cell on the uprising, were also killed.

Mr Ebrahim said the International Committee of the Red Cross and the Red Crescent had classified the situation as being an internal armed conflict or, in layman's terms, a civil war.

Such classifications show the situation has reached the threshold of a civil war in which all parties have responsibilities and obligations under international humanitarian law.

"The international community must urgently respond to the escalating violence in Syria in a stern and balanced manner, based on the realities on the ground," said Mr Ebrahim.

The Security Council should "express strong and unified support for Mr Annan and to call on all parties to cease the violence immediately", he added.

He said the UN Charter determined that the Security Council make proposals for conflict resolution without prejudice to the rights of the parties concerned. "South Africa will therefore support any decision of the Security Council that is balanced and geared towards supporting Mr Annan's call for all sides in the conflict to adhere to their commitments under his six-point plan."

The UN estimates that more than 10000 people, mostly civilians, have been killed in Syria since fighting started, with tens of thousands displaced.

With Reuters and Sapa