BEIRUT: China threw its weight behind U.N. envoy Kofi Annan on Wednesday, backing his call to include Iran in internationally-brokered talks to resolve Syria's crisis, in the face of strong Western opposition.

"China believes that the appropriate resolution of the Syria issue cannot be separated from the countries in the region, especially the support and participation of those countries that are influential on relevant sides in Syria," Foreign Ministry spokesman Liu Weimin said in Beijing.

U.N. Security Council veto-holders China and Russia have for the past year blocked efforts by Washington and its European and Gulf Arab allies to turn the screws on Syrian President Bashar Assad, fighting to defend his mostly Alawite ruling establishment against an uprising dominated by Sunni Muslims.

Assad's opponents say just under 13,000 armed and unarmed opponents of Assad, and around 4,300 members of security forces loyal to Damascus, have been killed since he launched a crackdown 16 months ago, using tanks and helicopter gunships to attack rebel strongholds inside Syria's biggest cities.

Activists on Wednesday reported a new bombardment of rebel areas of Homs, a hotbed of opposition to Assad, as well as fighting in many other parts of the country.

Annan was due to brief the Security Council at 1530 GMT on Wednesday on the results of a lightning diplomatic shuttle this week to Damascus, Tehran and Baghdad - three capitals forming a Shi'ite Muslim axis of power in the Middle East.

Annan plunged into a tussle between the major powers on Tuesday, insisting that Iran, which strongly backs Assad and is regarded as an adversary of the West and Gulf Arabs, had a role to play in the drive to relaunch stalled peace efforts and begin talks towards a political transition.

In Baghdad, Annan also won backing from Iraqi Prime Minister Nouri al-Maliki, who like Assad has close ties to Tehran.

Washington's reaction was not encouraging for the envoy.

"I don't think anybody with a straight face could argue that Iran has had a positive impact on developments in Syria," White House spokesman Jay Carney told reporters.

Russia and China oppose any external move to tip the balance against Assad by making his departure a condition of a political transition. Moscow's latest move in the game of diplomatic chess was to suggest on Tuesday that it could host regular meetings of an "action group" that would include the Syrian opposition.

Opposition leaders say there can be no peaceful transition unless Assad, who crushed popular protests from the moment they began, relinquishes power first. Assad, whose family has ruled Syria for 42 years, says he still has the backing of his people.

A delegation from the foreign-based opposition Syrian National Council was meeting Foreign Minister Sergei Lavrov in Moscow to urge Russia to drop its support for Assad.

Annan originally wanted Iran to be part of the first major power "action group" meeting, in Geneva on June 30, but the idea was vetoed at the time. France was not enthusiastic about the latest Russian proposal that it now meet regularly in Moscow.

"There must be a need for such a meeting for it to take place," said Foreign Minister Laurent Fabius. "After Kofi Annan's visit to Damascus, would it be more or less necessary? I can't say."

It was agreed at the Geneva meeting that a transitional government should be set up in Syria, but the major powers remain at odds over what part Assad might play in the process.

In New York, the 15-member Security Council must decide what to do with the U.N. mission in Syria, known as UNSMIS, before July 20 when its mandate expires. It is due to vote on July 18.

In April, it authorized deployment of up to 300 unarmed military observers to Syria to oversee a ceasefire, part of a six-point peace plan proposed by Annan. But the truce was never honored and the monitors are now confined to hotels.

Russia on Tuesday circulated to Security Council members a draft resolution to extend the mission for three months so it can shift focus from monitoring the non-existent truce to securing a political solution.

The draft was unlikely to satisfy the United States and European council members, who have called for a resolution under Chapter 7 of the U.N. Charter, which would allow the council to authorize actions ranging from diplomatic and economic sanctions to military intervention to enforce Annan's peace plan.

U.S. officials have said they are talking about sanctions, not military intervention.