The third summit of the Group of 20 (G20) kicked off in Pittsburgh, Pennsylvania, on Thursday evening. The leaders are expected to coordinate their positions on global economic recovery, financial regulatory reform and world trade issues during the two-day meeting.

A year after global finance crisis erupted, as countries claw back from recession, leaders of G20 is to decide when to pull the plug on state stimulus packages and how to coordinate that move.

Early this month, G20 finance ministers and central bank governors reached a consensus that, although the darkest time of global economic recession in the past 70 years has passed, the stimulus policy should continue until recovery is confirmed.

Leaders from the G20 will also coordinate on their macro economic policies to ensure the world economy will grow on a sustainable and more balanced pattern.

"In Pittsburgh, we will work with the world's largest economies to chart a course for growth that is balanced and sustained," said US President Barack Obama on Wednesday.

The summit will be key for financial reforms, said German Chancellor Angela Merkel on Thursday before departing for Pittsburgh, warning that efforts to make the world less prone to financial disasters may lose momentum.

White House spokesman Robert Gibbs also said on Thursday that financial regulatory reform is the most important topic for the summit.

"I think quite frankly it will be financial regulatory reform," said White House spokesman Robert Gibbs when asked to describe the most vital item for G20 action.

It's still unclear if Obama would reach agreement with his European counterparts on regulatory reform as EU leaders seek to put on tough rule in financial regulation.

Meanwhile, leaders from developing countries are expecting a stronger voice for developing countries in steering the world economy.

"If richer countries, such as the United States want the developing world's help in sorting out the financial crisis, then those nations are going to have to cede some of their controlling stake in the institutions devoted to the task, such as the International Monetary Fund," Brazilian President Luiz Inacio Lula da Silva told the United Nations on Wednesday.

India has urged the G20 summit to come out strongly against protectionism in trade while continuing reform of international financial institutions to give greater voice to developing countries.

As dozens of poor countries are still mired in an economic downturn and struggling to finance key needs, the summit will also talk about how to help them out of economic recession.

The G20 have advanced in some areas, but have not reached agreement on a number of issues. It need move faster, said Russian President Dmitry Medvedev earlier this week.