To be hosted by US President Barack Obama, the two-day meeting of G20 leaders will be the third since the implosion of the US investment bank Lehman Brothers about a year ago plunged the world into what has been dubbed the Great Recession.

But with the G20 government chiefs having laid down the markers for sweeping market reforms at their two previous meetings, European officials say the leaders heading to Pittsburgh want to see this week's summit agree to an action plan for implementing the proposed changes.

"There is a strong degree of unity on the need for concrete progress at the meeting in Pittsburgh," said German Chancellor Angela Merkel in the buildup to the summit which is due to begin Thursday.

"Every financial product, every financial institution and every financial centre should be subject to regulation, and this has to happen coherently and globally," said the chancellor, who has played a key role in drawing up the European agenda for the G20 summits.

Indeed, coming just days before Germany's national election, the Pittsburgh summit will present Merkel with the chance to represent Germany on the world stage and to reaffirm her credentials as an adept economic crisis manager.

Along with Merkel, British Prime Minister Gordon Brown, French President Nicolas Sarkozy, Italian Prime Minister Silvio Berlusconi and top European Union officials are heading up the European delegation in Pittsburgh.

Those attending the G20 conference will also include the leaders of Canada and Australia as well as the government chiefs of the world's emerging powerhouse economies such as China, India and Brazil.

Together the world leaders attending the summit in Pittsburgh head up economies representing about 85 per cent the world output.

However, since the G20 leaders last met in London six months ago, signs have emerged that the world economy is starting to shake off what has been its biggest downturn in a generation.

This in turn has raised concerns in Europe that the unexpected improvement in the global economy could reduce the sense of urgency for pressing on with a makeover of the financial system.

But underscoring Europe's commitment to bolster global market controls, the European Commission is expected to unveil Wednesday plans to create new supervisory bodies for overseeing Europe's markets and financial sector.

With Washington now joining Europe in promoting the need for the G20 to create a framework for sustainable growth, a commitment to coordinating measures is expected to be included in the summit's final communique to be unveiled in Pittsburgh on Friday.

Building on the accord reached at the G20 finance ministers' meeting in London earlier this month, the Pittsburgh summit is also expected to agree to continue to roll out the 5-trillion dollars in stimulus plans launched by governments around the world to combat the recession.

At the same time, the leaders are likely to agree to coordinate their moves on so-called exit strategies for retreating from the anti-crisis spending plans once they are confident the economic upturn has taken hold.

Likewise, the Pittsburgh summit should sign off on moves to introduce new stricter capital rules on the financial sector, which the Europeans see as lying at the heart of the summit.

Since the G20 leaders' first meeting in Washington last November, steps have been taken to fulfil a key part of Europe's agenda for reshaping the global financial order, which is a crackdown on so-called uncooperative territories such as tax havens.

However, the Pittsburgh summit is also expected to sidestep a clash over bonus payments with the G20 expected to accept new stricter conditions on executive's pay.

In particular, this is likely to be in line with a proposal essentially drafted up by Britain to defer bonus payments until an executive's performance can be assessed and to claw-back payments made for analysts and bankers taking excessive risks.

The G20 meeting also comes as world leaders gear up for a major summit on climate change later this year in Copenhagen.

As a result, the Pittsburgh summit agenda has also been extended to include the contentious issue of big industrial states offering financing to help emerging economies curb CO2 emissions.

European officials say, however, the G20 leaders are only expected to discuss financing measures to curb green gas emissions in Pittsburgh rather than reaching a decision.