Interior Minister Claude Gueant, former chief of staff to Sarkozy and one of his top advisors for the past four years, said Lagarde would make an excellent head of the Washington-based lender, becoming the first member of France's cabinet to openly tout her credentials.

The race for the leadership of the IMF was thrown open on Thursday, at a crucial time for Europe's debt crisis and the fragile global recovery, when Frenchman Dominique Strauss-Kahn resigned after being arrested on charges of attempted rape.

Strauss-Kahn, a leading contender for the French presidency until his arrest, has denied the charges. His departure opened a tug of war between Europe and emerging economies, which argue it is time to end 65 years of European domination of the post.

"I hope it will be a European and Christine Lagarde obviously has all the qualities to be an excellent director of the IMF. And besides, many countries support her," Gueant told Europe 1 radio.

While Lagarde's departure for Washington would rob Sarkozy of a charismatic minister a year ahead of presidential polls in France, it would hand him a powerful ally for France's ongoing presidency of the G20 and in euro zone debt-crisis talks.

With the IMF due to accept nominations from Monday, European powers have already started to close ranks behind a regional candidate, saying it is crucial the next managing director has knowledge of Europe, where the lender is heavily involved.

On Saturday, British finance minister George Osborne said Lagarde, a 55-year-old former lawyer, was an "outstanding candidate" and German Chancellor Angela Merkel called her an experienced "figure of excellent standing".

With the support of the region's three largest economies appearing to guarantee Lagarde the European nomination, she would only realistically require the backing of the United States to secure the IMF post.

Leaders from the G8 group of industrialised powers are expected to discuss a replacement for Strauss-Kahn at a summit this week in the French coastal resort of Deauville, but it was not yet clear if they would make any formal announcement.

LEGAL CLOUD

Lagarde has won admirers in Washington and Beijing for balancing the interests of advanced and developing economies during France's G20 presidency this year. Having worked in the United States as a lawyer for some 20 years, she also speaks flawless English.

Her chances received a boost on Friday when former Turkish economy minister Kema Dervis — seen as the leading emerging market candidate — ruled himself out of the running.

Mexico, however, is leaning towards nominating its central bank chief Agustin Carstens, a former deputy managing director at the Fund.

The finance ministers of Australia and South Africa, who jointly chair a G20 committee on reform of the IMF, said on Sunday the tradition that the fund's managing director was a European was out of date and called for G20 nations to honour a pledge made in Pittsburgh two years ago for an open selection.

Perhaps the gravest obstacle to Lagarde's prospects could come from a legal investigation into her decision to settle a dispute between the state and a businessman and friend of Sarkozy, who won a payoff of 285 million euros.

A panel of judges are expected to decide by mid-June whether to launch a formal investigation into the case, with Lagarde saying she is confident because she has done nothing wrong.

The IMF board has said a new chief would be appointed by June 30, allowing enough time to resolve the case.