US Ambassador John Danforth voiced confidence on Thursday in the embattled Annan at a time when Washington needs UN help to organise Iraqi elections next month.
"We are not suggesting the resignation or pushing for the resignation of the secretary-general," said Danforth, whose previous non-committal remarks had set off speculation that Washington wanted Annan's removal.
"No one, to my knowledge, has cast doubt on the personal integrity of the secretary-general. No one. And we certainly don't," he said.
"We are expressing confidence in the secretary-general and in his continuing in office."
US President George Bush had also declined to speak out in favour of Annan, who has been buffeted by a string of embarrassing UN scandals and targeted with calls for resignation by some US lawmakers.
Bush has conspicuously declined
to speak out in favour of Annan
While other nations were quick to defend Annan, the US - the lone superpower that is supposed to pay more into the UN budget than any other nation - had been conspicuously silent.
"What [Danforth] said reflects the views of the US government and is the product of consultations throughout the US government," a senior US Department of State official said.
"It was widely coordinated."
Danforth stressed that Washington remains concerned about the scandal, amid reports that some of the money Saddam Hussein siphoned off may now be funding armed fighters battling US and Iraqi forces in the war-torn country.
"There is a cloud over the United Nations," Danforth said. "There's no doubt about it."
Annan has been tainted by revelations about the oil-for-food
programme, under which the UN supervised the oil sales of Saddam Hussein's government.
Norm Coleman, the US senator leading a congressional probe into the scheme, called for Annan's resignation after saying he had evidence that the UN official who ran it had received payoffs from Baghdad.
"There is a cloud over the United Nations. There's no doubt about it"
US ambassador John Danforth
There has been no indication that Annan profited, but the UN
chief admitted there was a "perception problem" after it emerged his son Kojo kept receiving payments until February from a Swiss firm working under the programme.
Annan's spokesman has shrugged off calls by Coleman and others for the secretary-general's resignation, saying no member states in the 191-nation world body had made any such statement.
Paul Volcker, a former US Federal Reserve banking chairman appointed by Annan to head an independent inquiry, has rebuffed Coleman's calls to hand over documents immediately, saying he will do so later.