The International Monetary Fund is estimating it needs to raise up to $600 billion (389 billion pounds) in new resources to lend to countries struggling with the fallout from the growing euro zone debt crisis, IMF sources said on Wednesday.

While the IMF estimates it will need $500 billion of the money to lend to member countries in need, the remaining $100 billion will be used as a protection buffer, the sources, who were present at an IMF board meeting on the issue on Tuesday, told Reuters.

The IMF also estimated there would be a $1 trillion global financing gap over the next two years if global economic conditions worsened considerably, the sources added.

The IMF currently has a lending capacity of about $380 billion. IMF sources said a European commitment to inject 150 billion euros (129 billion pounds) into the IMF is included in the $600 billion figure.

When consulted, an IMF spokesman said: Based on staff's estimate of global potential financing needs of about $1 trillion in the coming years, the Fund would aim to raise up to $500 billion in additional lending resources. This total includes the recent European commitment of about $200 billion in increased Fund resources.

At this preliminary stage, we are exploring options on funding and will have no further comment until the necessary consultations, he added.

On foreign exchange markets, the reports of plans for increased IMF lending capacity helped boost the euro.

The new figures comes as G20 deputies from developed and developing nations gather in Mexico on Wednesday for preliminary talks on boosting the IMF's war chest, with concerns that the European policymakers have not come up with a comprehensive plan to assure investors they have a handle on the problems.

Emerging market countries such as China and Brazil have said they are willing to contribute new resources to the Washington-based institution in exchange for greater voting power.

Getting more resources from advanced economies, such as the United States, is going to be difficult, if not impossible. With a strained budget at home, some U.S. congressional Republicans have threatened to yank $100 billion in U.S. money to the IMF if the funds are used to bailout more euro zone countries.

The Obama administration is unlikely to want to take on the issue as the president seeks reelection this year.

IMF Managing Director Christine Lagarde said on Tuesday she met with the IMF board to assess whether the global lender needs additional funds to respond effectively to the euro zone crisis and said IMF management would explore options for increasing the Fund's firepower.

The IMF has warned it will cut global growth projections for 2012 when it updates its forecast on January 24. Weakening global growth prospects raises fears that more countries will need rescuing by the IMF, especially if capital markets freeze up completely.

The World Bank warned in its annual growth outlook late on Tuesday that Europe appears to already be in recession and developing countries should brace for a slowdown in their economies, especially Brazil and India and to a lesser extent Russia, South Africa and Turkey.

With credit downgrades in nine euro zone countries by Standard & Poor's last week, including for France, and uncertainty over Greek debt talks that risk pushing the country into default, the IMF board has urged euro zone leaders to take steps to contain the crisis.

The board called for policies that would address the European crisis and for euro zone policymakers to make sure there is enough money available to tackle the bloc's debt problems effectively.

(Reporting By Lesley Wroughton; Editing by W Simon)