The Group of 20 said the global economy was improving but it was too early to declare an end to crisis with emerging markets facing increasing volatility.

Leaders of the G20 acknowledged the troubles faced by some emerging nations but said it was up to them, first and foremost, to put their own houses in order.

The G20 groups developed and emerging economies accounted for 90% of the world economy and two-thirds of its population.

The prospect that the Federal Reserve may rein in its expansive monetary policies as soon as this month has plunged into turmoil some emerging economies that had enjoyed rapid growth thanks in part to a flood of cheap dollars.

Emerging and developed G20 powers in St Petersburg struggled to find common ground over the turbulence unleashed by the prospect of the US reducing its money printing.

A communique issued at the end of the two-day summit stuck closely to the statement issued by finance ministers in July, demanding changes to monetary policy must be "carefully calibrated and clearly communicated".

The G20, which united in response to global crisis in 2009, now faces a multi-speed recovery with the US economy pushing ahead, Europe maybe finding a floor but developing economies facing blowback from the looming 'taper' by the Fed.

As the communique was released, markets were fixated on the monthly US jobs report which came in weaker than expected, complicating the Fed's decision on whether to scale back its massive monetary stimulus later this month.

Demands led by Germany for binding targets to extend the Toronto debt reduction goals agreed at a summit hosted by Canada in 2010, fell on deaf ears as the focus has shifted firmly towards promoting growth.

"Medium-term fiscal strategies ... will be implemented flexibly to take into account near-term economic conditions, so as to support economic growth and job creation, while putting debt as a share of GDP on a sustainable path," the communique said.

New elements referred to a growth initiative proposed by Australia, which assumes the G20 chair next year, a proposal to tighten regulation of so-called 'shadow banking' and extending a deadline on reining in trade protectionism.

The summit debate on the health of the world economy, chaired by Russian President Vladimir Putin on Thursday evening, was difficult and reflected concerns about a growth slowdown in the developing world.

"The most difficult and time-consuming discussions related to the evaluation of the situation of global economy," Andrei Bokarev, head of the Finance Ministry's international department said.

The BRICS group of large emerging economies - Brazil, Russia, India, China and South Africa - agreed to chip $100 billion into a currency reserve pool that could help counter a possible balance-of-payments crisis.

But the facility is a drop in the ocean compared to the trillions traded in foreign exchange daily and it is likely to be next year at the earliest before it is finalised.

Early signs of a turnaround in Europe after a sovereign debt crisis and slump in parts of the euro zone kept the region's leaders out of the firing line for the first time in three years. "I want to tell you, at this G20 we were no longer the focus of attention," said European Commission President Jose Manuel Barroso.

G20 to crack down on firms who use tax havens

The leaders of the world's 20 largest economies also committed to crack down on cross-border companies that use tax havens.

In today's communique, the G20 leaders said they were committed to an action plan to address "base erosion."

Low tax payments by major global companies such as Google or Amazon have sparked public anger in Europe.

The G20 will be commissioning recommendations to set up a system so that profits would be taxed "where economic activities deriving the profits are performed and where value is created."

The leaders also agreed on a plan to share information on individual taxpayers. They said they expect to begin exchange information automatically on tax matters among G20 members by the end of 2015.