Advanced and developing nations alike are keen for reassurances that the European Union will do whatever it takes to limit fallout from the crisis and convincing answers could help officials inch closer to boosting the firepower of the International Monetary Fund (IMF) so it can better help victims.

U.S. Treasury Secretary Tim Geithner and Financial Stability Board Chairman Mark Carney are among those scheduled to attend the February 25-26 meeting, along with officials from developing powers such as Brazil, India and China, whose support is crucial for any boost to IMF resources.

But G20 finance ministers and central bankers are not expected to decide specifics when they gather in Mexico City ahead of talks between EU leaders on their firewall plans the following week.

"It is highly unlikely that the G20 will reach a concrete agreement on IMF funding this month," one official from the bloc said. "It's impossible that a decision on IMF resources could come first before the euro zone comes up with its own firewall."

The IMF is seeking to more than double its firepower by raising an extra $600 billion to help countries deal with the fallout from the debt crisis, but the plan faces resistance from countries including the United States and Canada.

Many countries outside the 17-member euro zone say the region must first put up more of its own money to contain contagion, for example by combining the lending abilities of its two bailout funds, which together would add up to about 750 billion euros ($992 billion) of still-uncommitted funds.

EU leaders will decide whether to combine the temporary and permanent funds at a March 1-2 summit and draft conclusions seen by Reuters show they plan to call for the G20 to boost IMF funds in April, when policymakers meet again in Washington.

Analysts also see little chance of major progress at the meeting given the down-to-the-wire negotiations over every step of Europe's response to the debt crisis so far.

"It's all about Greece, the euro zone crisis and containing contagion from that," Capital Economics economist Neil Shearing said. "The expectations bar is very low."

HINT AT STRONGER FIREWALL

Still, in a nod to concern about Europe's determination to tackle the crisis, which has knocked more than 10 percent off the euro in just over two years, a second G20 source said Europe was prepared to hint at a stronger firewall -- paving the way for the February 26 communique to include at least a reference to boosting IMF resources.

The official said about $250 billion of the extra IMF funding would come from Europe and the onus was on China and Japan to provide most of the rest, with small contributions also possible from Brazil, Argentina, Switzerland and Australia.

Japanese Finance Minister Jun Azumi said on Tuesday policymakers were not yet at the stage of deciding the size of individual contributions and other G20 officials who spoke on condition of anonymity also saw no details being discussed until April, the last chance before a G20 leaders' summit in June.

"It is possible we will have only a 'tour of the table' on increasing IMF resources at next Saturday's meeting," a third G20 official said.

Policymakers also play down the chance of a tougher stance on currency flexibility, a big theme in past years as countries such as the United States sought to put pressure on China to let the yuan appreciate.

This year, the issue has been overshadowed by the euro zone crisis, not least because of hopes that China will dip into its reserves to give an extra $100 billion to the IMF -- a donation which will probably come at a price.

At the weekend meeting, the first of finance ministers and central bankers under Mexico's presidency, there will be pressure on the Europeans to show they mean to keep a promise to cut their over-representation at the IMF in favor of developing countries.

Mexico has promised a trimmed-down, back-to-basics G20 program but talks will still include topics ranging from the global economic outlook to international financial institutions, increasing access to banking services and financial education for developing countries.

G20 policymakers will be briefed on progress towards making financial operators on the fringes of the traditional bank system hold more capital as part of stronger rules for the $60 trillion shadow banking sector.

Leaders from the G20 countries have asked their regulatory task force, the Financial Stability Board, to come up with recommendations for regulating shadow banking, which involves credit, leverage and deposit-like funding on a large, lightly regulated scale.

Delegates may also discuss possible candidates to succeed Robert Zoellick as World Bank president when he steps down in June, although it is unlikely that emerging markets would field a candidate to challenge seriously the U.S. hold on the global lender's leadership. (1 euro = $1.3227)

(Additional reporting by Francesca Landini in Milan, Jan Strupczewski in Brussels, Tetsushi Kajimoto in Tokyo and Louise Egan in Ottawa; Editing by Robert Birsel)

• A Permanent Economic Emergency