Russia said on Tuesday that President Bashar al-Assad could leave power as part of a settlement to end bloodshed in Syria, as Saudi Arabia called on Moscow to end its support for his embattled regime.
Moscow is under growing pressure to back Assad's departure as a first step in a peace accord that would see his inner circle assume command in the interim, based on a UN-backed transition this year in Yemen.
"We have never said or insisted that Assad necessarily had to remain in power at the end of the political process," said Russia's Deputy Foreign Minister Gennady Gatilov.
"This issue has to be settled by the Syrians themselves," ITAR-TASS news agency quoted him as saying.
The statement was one of Russia's most explicit about Assad's position since Foreign Minister Sergei Lavrov refused to clearly back his rule during a visit to Damascus in February.
It came as Moscow and Beijing, which have stalled Western-led moves against Damascus, began talks on ending nearly 15 months of violence that has killed more than 13,500 Syrians, and cost the lives of at least another 47 on Tuesday.
US Secretary of State Hillary Clinton urged both Russia and China to be "part of the solution" to the crisis after they agreed to work together more closely in the United Nations.
"We believe there is a way forward and we are ready to pursue that. And we invite the Russians and the Chinese to be part of the solution," she told a news conference in the Georgian Black Sea city of Batumi.
Russian President Vladimir Putin held talks with President Hu Jintao, a day ahead of a meeting with Hu's likely successor Vice President Xi Jinping.
China's UN envoy said on Monday that efforts to end the bloodshed were at a "crossroads," and that government and opposition forces must halt violence.
Both Beijing and Moscow, which have twice used their veto powers to block tougher action against Assad's regime at the UN Security Council, have come under intense pressure to change their stance since last month's Houla massacre.
China's ambassador Li Baodong said the massacre of at least 108 people, most of them women and children, had dealt a huge blow to UN-Arab envoy Kofi Annan's peace mission, as Beijing took over the chair of the Security Council for June.
Li told reporters, without signalling any easing in China's opposition to sanctions against Assad: "The political process to solve the Syrian crisis is at a crossroads."
The Houla massacre "has caused collateral damage to Annan's mediation effort. And also it presents a huge challenge to the international community," Li said.
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Saudi Arabia, which has led Arab calls for Assad to step aside, said it was time for Moscow to change its tune on Syria and work to ensure the peaceful transfer of power in the unrest-swept country.
"The time has come for Russia to change its stance from supporting the Syrian regime to working to stop the killing and (supporting) a peaceful transition of power," said Foreign Minister Saud al-Faisal.
Germany called for tougher action at the UN Security Council.
"In my view we have to further step up the pressure on the Assad regime," Foreign Minister Guido Westerwelle said on a visit to the United Arab Emirates.
"We should seriously consider a Security Council resolution under Chapter Seven of the United Nations charter. Such a resolution could introduce non-military but nonetheless globally binding measures."
Bloodshed has persisted in Syria despite a UN-backed peace plan brokered by Annan that put almost 300 observers on the ground.
Access has been more restricted for aid agencies, however, and the United Nations said on Tuesday that Syria has now allowed them to visit four trouble spots.
"We will have a presence in Homs, Idlib, Daraa and Deir Ezzor to start with," said John Ging, of the UN Office for the Coordination of Humanitarian Affairs.
On the ground, clashes in Syria's western Latakia province killed 22 soldiers on Tuesday, the Britain-based Syrian Observatory for Human Rights said.
Asked about the high number of troop deaths, the Observatory's Rami Abdel Rahman told AFP: "Troops are vulnerable to heavy losses because they are not trained for street battles and are therefore exposed to attacks.
"What exacerbates those losses is that the army is fighting residents of those towns and villages, whether military defectors or civilians who took up arms against the regime, who know the area inside out and enjoy public support," he added.
The fighting came after the military suffered major weekend losses to the rebel Free Syrian Army which announced it was resuming "defensive operations" because of the failure of the UN-backed April 12 ceasefire.
Politically, Damascus declared as personae non gratae diplomats of several major Western states and Turkey, in a tit-for-tat expulsions following the Houla massacre on May 25-26.
Announcing the move against the ambassadors of the US, Britain, France and Turkey, among others, Syria said it "still believes in the importance of dialogue based on principles of equality and mutual respect" and that diplomacy is a "necessary tool" for countries to resolve disputes.