Mr Strauss Kahn
The IMF chief charged with a sex attack on a hotel maid has resigned from his post ahead of a new bail hearing in New York.
Dominique Strauss-Kahn maintained his innocence in a formal letter to the organisation and said he was quitting with "infinite sadness".
"I think at this time first of my wife - whom I love more than anything - of my children, of my family, of my friends," he said.
"I think also of my colleagues at the fund - together we have accomplished such great things over the last three years and more.
"To all, I want to say that I deny with the greatest possible firmness all of the allegations that have been made against me."
The 62-year-old French citizen - who had been a strong contender for the country's presidency in 2012 - added he would devote "all my strength, all my time, and all my energy" to proving his innocence.
There had been widespread speculation over the future of Strauss-Kahn after he was arrested following the alleged attack at the Sofitel hotel in New York at the weekend.
He faced growing pressure to quit as further claims about his private life emerged - including allegations by writer Tristane Banon that he attempted to rape her in 2002.
He is due at a fresh hearing today, where his lawyers will propose $1m bail - which was earlier refused by a judge - and electronic tagging. He has also waived his extradition rights.
Strauss-Kahn is reportedly on suicide watch at New York's Rikers Island prison, although he is not believed to have attempted to harm himself.
His lawyer, William W Taylor, said on Wednesday that his client's mood was "serious but good".
"He is a strong man and he's committed to seeing this through," he added.
There had been fears that without a suitable figure at the helm of the IMF, the organisation - designed to maintain stability in the world economy - could be thrown into disarray just as it attempts to tackle the eurozone debt crisis.
Among the possible candidates touted to replace Strauss-Khan is former prime minister Gordon Brown.
The IMF said it would discuss in the near future the process of selecting a new managing director. For now John Lipsky remains the acting chief.
Strauss-Kahn faces charges of committing a criminal sexual act, attempted rape, sexual abuse, unlawful imprisonment and forcible touching, all of which he denies.
The alleged victim, a 32-year-old widow from West Africa, testified on Wednesday before a grand jury.
It will decide in secret whether there is enough evidence to formally press charges.
A mugshot of Strauss-Kahn taken more than 24 hours after he was pulled from a plane at New York's JFK airport and detained on Saturday, showed him exhausted, his eyes downcast and half-closed.
Polls released in France on Wednesday showed 57% of respondents thought the Socialist politician was definitely or probably the victim of a plot.