Turkish Foreign Minister Feridun Sinirlioglu (L), U.S. Secretary of State John Kerry (2nd L), Saudi Foreign Minister Adel al-Jubeir (3rd L) and Russian Foreign Minister Sergey Lavrov pose during a photo opportunity before a meeting in Vienna, October 23, 2015. REUTERS/Carlo Allegri

By Arshad Mohammed and Francois Murphy

VIENNA (Reuters) - U.S. Secretary of State John Kerry said on Friday he expects new talks on Syria to begin as soon as next week, and did not rule out participation by Iran, President Bashar al-Assad's closest ally, which has been kept away from past peace conferences.

Along with counterparts from allies Saudi Arabia and Turkey, Kerry met for two hours on Friday in Vienna with Sergei Lavrov, foreign minister of Russia, which has transformed momentum in the 4-year-old Syrian civil war by bombing Assad's enemies.

So far all diplomatic efforts to end the conflict have foundered over the demand by the United States, European countries, Arab states and Turkey that Assad leave power as a pre-condition for peace, which he refuses to consider.

"What we agreed to do today is to consult with all parties

and aim to reconvene, hopefully as early as next Friday, with a broader meeting in order to explore whether there is sufficient common ground to advance a meaningful political process,” Kerry told reporters.

“I am convinced ... that today’s meeting was constructive and productive and succeeded in surfacing some ideas, which I am not going to share today, but which I hope have a possibility of ultimately changing the dynamic."

Asked if a meeting next week could include Iran, Kerry said he would not speculate on who might attend. But he added: “We want to be inclusive and err on the side of inclusivity rather than exclusivity.”

Iran has not been invited to previous international peace conferences on Syria, all of which ended in failure, while the war, which has so far killed more than 250,000 people and driven millions from their homes, has raged on.

Russia has long maintained that Iran should be included in Syrian peacemaking. Lavrov said he hoped Iran, as well as Egypt, would be invited to the next round of talks.

"We requested that future contacts take place in a more representative format," he said in comments broadcast on Russian television.

Saudi Arabian Foreign Minister Adel al-Jubeir said Friday's meeting had failed to achieve consensus over the future of Assad. Kerry, too, acknowledged wide differences with Moscow and Tehran over the future of the Syrian leader.

“Diplomacy has a way of working through very difficult issues that seem to be absolutely contradictory and, on their face, begin at odds. And this is one of those issues where the statements clearly - and current positions - are at odds,” Kerry said. “But if we can get into a political process, then sometimes these things have a way of resolving themselves.”

STRATEGY UPENDED

Russia's decision to enter the conflict with air strikes has upended the strategy of the United States and its regional and European allies.

Washington is leading its own bombing campaign against Islamic State fighters who control swathes of eastern Syria and northern Iraq, so the Russian intervention means the Cold War-era superpower foes are now flying combat missions in the same air space for the first time since World War Two.

Washington and Moscow both say they are targeting Islamic State, but they have opposing visions of Syria's future, with Washington saying Assad must leave power to bring peace and Russia describing his government as a bulwark against militants.

Russia describes all its bombing targets as belonging to Islamic State. The United States and its allies say the overwhelming majority of Russian strikes have targeted other groups opposed to Assad, including groups they have backed.

By tipping the balance of power on the battlefield in Assad's favour and making it less likely that his enemies will be able to drive him out, Moscow clearly hopes to improve his position in future talks.

Winning a seat at the negotiating table for Assad's main backer Iran would be a major diplomatic victory. The U.S. position in the past has been that Tehran could play a part in Syrian diplomacy but only if it was prepared to act in a way Washington viewed as constructive.

Iran, which has furnished advisers to aid Assad's forces on the ground and encouraged its Lebanese Shi'ite Hezbollah allies to fight on behalf of Damascus, repeated its position on Friday that Syrians must pick their leader - code for supporting Assad who has held elections which he overwhelmingly won.

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