US President Barack Obama is trying to swing the G20 spotlight back onto global imbalances and take his own country's policies out of the glare as world leaders gathered in Seoul today.

Obama, facing widespread criticism of the US 'easy-money' policy as he arrived for the two-day Group of 20 leaders summit, said a strong US economy was vital to the global recovery and urged his G20 counterparts to put aside their differences and do their part to bolster growth.

'When all nations do their part - emerging no less than advanced, surplus no less than deficit - we all benefit from higher growth,' Obama said in a letter sent to G20 leaders yesterday.

The bridge building came after a day of heated arguments as negotiators struggled to hammer out a closing statement that all G20 leaders could sign.

Deep divisions have emerged over economic policy, particularly the US Federal Reserve's decision last week to spend another $600 billion buying government bonds. Critics say the Fed's policy weakens the dollar to the detriment of other nations, but Obama said the dollar's strength ultimately rests on the strength of the US economy.

The Group of 20 leaders had hoped this week's gathering, the fifth since the financial crisis exploded in 2008, would mark the beginning of a new era of global cooperation. Hosts South Korea printed banners proclaiming a slogan of 'Shared Growth Beyond Crisis'.

But the unity forged in crisis has given way to diverging national policies that reflect a multi-speed recovery from the recession, prompting critics to question the effectiveness of the G20 grouping itself.

In his G20 letter, Obama sought to return the discussion to global imbalances and insisted that the US was not the only country that must change its ways in order to drive a stable, strong recovery.

'Just as the US must change, so too must those economies that have previously relied on exports to offset weaknesses in their own demand,' he wrote in a thinly veiled reference to China.

Most major economies are grappling with sub-par growth, leaving them reliant on exports, while emerging powers such as China and Brazil have roared back to pre-recession strength.

The US got some support from close ally Britain. Finance Minister George Osborne said a strong US economy was in the best interest of Asia and the world, echoing Obama.