PITTSBURGH: Leaders of the world's biggest countries began arriving for the Group of 20 (G20) summit yesterday to seek ways to nurture a recovery from the worst recession since the 1930s and build safeguards against future catastrophes.

US President Barack Obama, hosting his first G20 summit, will lay out a massive agenda that includes tackling one of the thorniest problems facing the global economy - how to even out massive imbalances between export powerhouses such as China and the deeply indebted United States.

The sheer volume of problems the two-day summit is set to address - from the lopsided global growth model to climate change, tougher financial regulation and caps on bankers' pay - means expectations for any near-term action are low.