US president Barack Obama and Russian president Vladimir Putin today agreed on the need to end violence in Syria but showed no concrete signs of narrowing their differences on tougher sanctions against Damascus.

After a week of Cold War-style recriminations between US and Russian diplomats, the talks at a Group of 20 summit in Mexico tested whether the two leaders could forge a working relationship and find common ground on Syria and other festering disputes.

Mr Putin frowned and Mr Obama wore a sober expression during their remarks to reporters after the meeting. "We agreed that we need to see a cessation of the violence, that a political process has to be created to prevent civil war," Mr Obama told reporters, who entered the room after the talks went on for some two hours - longer than originally planned.

"From my point of view, we have found many common points on this issue [of Syria]," Mr Putin said, adding the two sides would continue discussions.

With Syrian president Bashar al-Assad continuing his bloody, 15-month crackdown on the opposition, Mr Obama and Western allies want veto-wielding Moscow to stop shielding him from further UN Security Council sanctions aimed at forcing him from power.

Mr Putin, a former KGB spymaster, is suspicious of US motives, however, especially after the Nato-assisted overthrow of Libyan leader Muammar Gadafy last year, and he has offered little sign of softening his stance on Syria.

World leaders at the G20 summit are also set to increase pressure on Europe to outline a lasting strategy to save the euro currency after a victory for pro-bailout parties in a Greek election failed to calm financial markets.

Mr Obama spoke with European leaders after the Greek vote and requested a meeting with them this evening, underscoring the extent of concern in Washington that the euro crisis could deepen, infecting the fragile US economy only months before an election.

He will also hold separate talks with German chancellor Angela Merkel, who as the leader of Europe's biggest economy, faces enormous pressure to take bold new steps to resolve a crisis that has been raging for more than two years.

Protected by Mexican navy vessels and troops on the beaches and highways, Group of 20 leaders from major industrialised and developing economies, representing more than 80 per cent of world output, began a two-day meeting in the Pacific resort of Los Cabos, Mexico, to prioritise growth and job creation against the backdrop of a weakening global economy.

A narrow victory for the conservative New Democracy party in the Greek election yesterday eased concerns the heavily-indebted country could exit the euro zone soon but did little to calm financial markets.

The euro fell from a one-month high against the dollar and Spanish bond yields shot above 7 per cent to their highest level since the creation of the single currency in 1999.

British prime minister David Cameron, who runs the biggest European economy outside the euro zone, is poised to warn leaders from the currency area that they faced "perpetual stagnation" without bold new measures and to call on central banks to protect the global economy.

"We cannot afford for central banks around the world to stand on the sidelines if we are to deliver the growth we need," Mr Cameron will say, according to extracts of a speech.

"It is becoming increasingly clear in the euro zone that the core, including the ECB [European Central Bank], must do more to support demand and share the burden of adjustment."

Ms Merkel, who touched down in Los Cabos early today, faces intense pressure to take stronger action but has rejected calls for joint euro zone bonds and the creation of a "banking union" in Europe with cross-border deposit guarantees.

Germany has sent signals it could be open to giving Greece a bit more time to get its deficit under control, but it is not budging on the substance of strict budget cuts and structural reforms that Athens has pledged to implement in exchange for two successive EU/IMF bailouts worth a combined €240 billion.

That could put Ms Merkel on a collision course with the winner of the Greek vote, Antonis Samaras, who campaigned pledging to renegotiate elements of the rescue and reiterated that stance today.

Reuters