US President Barack Obama faced growing pressure from world leaders not to launch military strikes in Syria on Thursday at a summit on the global economy that was eclipsed by the conflict.
The Group of 20 (G20) developed and developing economies met in St. Petersburg to try forge a united front on economic growth, trade, banking transparency and fighting tax evasion.
But the club that accounts for two thirds of the world's population and 90 percent of its output is divided over issues ranging from the US Federal Reserve's decision to end its programme of stimulus for the economy to the civil war in Syria.
Russian President Vladimir Putin wants to use the meeting in a seafront tsarist palace to talk Obama out of military action against Syrian President Bashar al-Assad over a chemical weapons attack which Washington blames on government forces.
Obama wore a stiff smile as he approached Putin on arrival at the summit and grasped his hand. Putin also maintained a businesslike expression. It was only when they turned to pose for the cameras that Obama broke into a broader grin.
The first round at the summit went to Putin as China, the European Union and Pope Francis - in a letter for G20 leaders - aligned themselves more closely with him than with Obama over the possibility and legitimacy of armed intervention.
"Military action would have a negative impact on the global economy, especially on the oil price - it will cause a hike in the oil price," Chinese Vice Finance Minister Zhu Guangyao told a briefing.
The Pope urged the leaders to "lay aside the futile pursuit of a military solution". He has also invited the 1.2 billion Roman Catholics and people of other faiths to join him in a day of prayer and fasting on Saturday to end the civil war.
European Union leaders, usually strong allies of the United States, described the Aug. 21 attack near Damascus, which killed an estimated 1,400 people, as "abhorrent" but added: "There is no military solution to the Syrian conflict." .
Putin, Assad's most important ally, was isolated on Syria at a Group of Eight meeting in June, the last big meeting of world powers. He could now turn the tables on Obama, who recently likened him to a "bored kid in the