Dominique Strauss-Kahn faced growing pressure to quit as head of the IMF after his arrest on attempted rape charges, as some French politicians expressed outrage over his treatment by US authorities.

The battle to succeed Strauss-Kahn, who is alone in a cell at New York's notorious Rikers Island jail, heated up when China, Brazil and South Africa challenged Europe's long-standing grip on a job that is pivotal to the world economy.

The IMF chief is expected to remain in the jail, known for its gang violence, at least until his next appearance in court on Friday, when his lawyers may again request bail.

It could be six months before a trial begins, legal experts said. A law enforcement source said Strauss-Kahn was under suicide watch as a precautionary measure.

The IMF said it had not been in touch with Strauss-Kahn since his arrest, but believed it would be important to do so 'in due course.' Two IMF board sources told Reuters the board would ask Strauss-Kahn whether he planned to continue in his post.

One of the sources said it would be ideal if Strauss-Kahn resigned. The second source said that sentiment was not shared across the 24-member board, which has the authority to remove him.

Strauss-Kahn is accused of a violent sexual attack on a maid who came to clean his luxury suite at the Sofitel hotel in Manhattan on Saturday, and of trying to rape her. His lawyer has said he will plead not guilty. If convicted, he could face 25 years in prison.

In the US, which is the IMF's biggest shareholder, politicians began questioning the viability of his tenure as head of the institution charged with managing the world economy and central to negotiating debt crisis deals.

'I can't comment on the case, but he is obviously not in a position to run the IMF,' US Treasury Secretary Timothy Geithner said.

John Lipsky, the second in command, is in charge during Strauss-Kahn's absence, but no formal interim chief has been named. IMF sources told Reuters that David Lipton, White House international economic adviser and former deputy treasury secretary, would take Lipsky's deputy position.

Strauss-Kahn's arrest has thrown the IMF into turmoil just as it is playing a key role in helping euro zone states like Greece and Portugal tackle debt woes.

Senate Foreign Relations Committee Chairman John Kerry stopped short of calling for Strauss-Kahn's resignation, but he called the circumstances of the case 'troubling if not damning.'

'If the evidence is what it appears to be, I think it would be very difficult for him to manage' as IMF head, Kerry said.

In Europe, Strauss-Kahn was also losing support.

'Given the situation, that bail has been denied, he has to consider that he would otherwise do damage to the institution,' said Austrian Finance Minister Maria Fekter.

Spanish Economy Minister Elena Salgado cast doubt on Strauss-Kahn's judgment, and said it was up to the IMF chief to make a decision on resignation.

'That is a decision which it is to up to Mr. Strauss-Kahn to take, but the crimes he is accused of are very serious... My solidarity first and foremost is with the woman who suffered the attack, if that was what happened,' she told reporters.

But in France, President Nicolas Sarkozy urged center-right lawmakers at a closed-door breakfast to show 'restraint and dignity' and refrain from comment on the Strauss-Kahn case, participants said.

The lawyer for the alleged victim, 32, said she was traumatized and in hiding. He said she was a widow with a 15-year-old daughter, who moved to New York from the West African nation of Guinea about seven years ago, he said.

'She didn't have any idea who he was or have any prior dealings with this guy,' Jeffrey Shapiro, a New York personal injury lawyer, told Reuters. – Reuters