World leaders struggled to inject confidence into the global economy at a G20 summit in Mexico dominated by a spiralling European debt crisis that is spooking markets and paralysing growth.
Mexico's President Felipe Calderon welcomed the likes of US President Barack Obama, newly returned Russian leader Vladimir Putin and German Chancellor Angela Merkel.
Two days of talks began with US officials saying there had been a clear change in European thinking towards more growth-friendly policies and Obama saying he was "encouraged" by what he had heard of Europe's plans.
In an effort to build confidence in the frail global economy, the G20 leaders said they "will act together to strengthen recovery and address financial market tensions", according to a leaked copy of their draft statement.
"All G20 members will take the necessary actions to strengthen global growth and restore confidence," it said.
The optimistic language, however, could do little to hide the dismal economic backdrop, with the focus already shifting to Spain and its sky-high cost of borrowing after the brief respite provided by Greece's positive election result.
In Sunday's pivotal polls in debt-ridden Greece, parties committed to the terms of their European Union and IMF-led bailout held off a strong challenge by a leftist anti-austerity party.
The International Monetary Fund has indicated that it could now be open to a renegotiation of Greece's 130 billion euros ($A162.52 billion) bailout program.
But hopes that the Greek vote had helped the single currency bloc turn a corner in the crisis were dashed as attention moved onto the fragile economies of other EU members and Spanish borrowing costs soared to record levels.
Italian and Spanish stocks plunged and the euro fell against the dollar.
Obama, who fears the turmoil in Europe will drag down the broader world economy and torpedo his hopes of re-election in November, was to hold a separate meeting later Monday with European Union leaders to address the crisis.
"The president was encouraged by what he heard regarding ongoing discussions in Europe about the path they are pursuing to address the crisis," White House spokesman Jay Carney told reporters after Obama met Merkel on the G20 sidelines.
Merkel, leading Europe's largest economy, has emphasised financial responsibility, while Obama, along with French President Francois Hollande, have put a focus on growth.
"We're seeing a noticeable shift in the European discussion regarding the critical importance of supporting demand and job growth," senior US treasury official Lael Brainard told reporters.
But Merkel gave no indication that she was about to abandon her hardline stance on the austerity measures Europe imposed on indebted eurozone members, which some argue have sabotaged economic growth.
"Elections cannot call into question the commitments Greece made. We cannot compromise on the reform steps we agreed on," she said.