World leaders are meeting in London on 2 April at the G20 summit to discuss plans to tackle the current economic crisis. We explain why the meeting has been called and what it hopes to accomplish.
What is the G20?
The G20 is a group of the world's most powerful countries that together represent 85% of the world's economy. It includes both major industrial powers such as the US and Germany, and emerging economic powers such as Brazil and China.
The UK government, which holds the rotating presidency of the G20, is organising the London summit to tackle the growing economic crisis with coordinated action.
It follows the first G20 meeting of heads of government which took place last November in Washington.
The G20 was originally set up after the Asian financial crisis in 1999 to discuss international co-operation among finance ministers and central bankers.
What are the aims of the London summit?
Gordon Brown believes that the aim of the London summit is no less than the redesign of the world financial system to respond to the downturn.
There are three main aims of the summit.
First, co-ordinated action to revive the world economy, both by more interest rate cuts and more spending by governments to bring countries out of recession.
Secondly, there will be efforts to prevent a future crisis by strengthening the international regulation of banks and other financial institutions.
Thirdly, leaders are hoping to agree a blueprint for future reform of the world financial system, including changes to the international organisations charged with regulating the world economy, such as the International Monetary Fund (IMF), to give a greater voice to poorer countries, and more resources.
Overall, it is hoped that the summit will prevent a slide towards protectionism by giving countries hope that working together could be a more effective way of dealing with the downturn.
What are the main obstacles to any deal?
Expectations of a comprehensive deal have been downplayed in recent days.
The most controversial issue is how far governments are prepared to go to agree further public spending to boost growth.
European countries, in particular, are resisting the calls from the US to promise to spend more not only this year but in 2010.
Restructuring the international financial institutions is also likely to be controversial, as giving more power to emerging market countries such as China and Brazil would mean taking away power and influence from European countries in the IMF and World Bank.
And there is yet to be agreement on how much more money should flow to poor countries who have been hard-hit by the downturn.
And although countries will say they are against protectionism in general, policing that agreement could be problematic.
What is likely to happen?
The summit is likely to produce a broad agreement on the need for coordinated action, but no concrete blueprint for future action.
With many countries already launching global stimulus plans, it may be relatively easy to agree to support such measures in principle.
The summit will agree a blueprint for the reform of the financial system that will put in place stronger global regulation - but that will take several years to implement.
And it is likely to endorse changed to the international financial institutions like the IMF, giving them more money and giving more voting rights for emerging countries like China.
There are unlikely to be any concrete measures to curb the fluctuations in exchange rates, which have hit many developing countries hard, although they may be pledges to maintain the flow of aid.
And there will be a general endorsement of the need to avoid protectionism, but it is unlikely to be enough to restart the world trade talks that have been stalled for the last year.
Full membership of the G20: Argentina, Australia, Brazil, Canada, China, France, Germany, India, Indonesia, Italy, Japan, Mexico, Russia, Saudi Arabia, South Africa, South Korea, Turkey, the United Kingdom, the US and the EU.