United Nations ? The United States and its military allies on Thursday challenged U.N. Secretary-General Kofi Annan’s statement that last year’s invasion of Iraq was an illegal act that violated the U.N. Charter, and they defended their decision to topple Saddam Hussein’s regime.

Annan made his comments Wednesday when a reporter for the BBC questioned him about the war’s legality, saying “from our point of view and the U.N. charter point of view, it was illegal.” The U.N. chief had previously voiced his opposition to the invasion on grounds that it lacked Security Council approval, which he maintains is required by the U.N. Charter, and has challenged White House claims that the war has made the world safer from international terrorists.

Annan also warned that the United Nations may not be able to effectively oversee Iraq’s elections next January if security does not improve.

“You cannot have credible elections if the security conditions continue as they are now,” Annan said.

The remarks about the war’s legality provoked a swift reaction from U.S., British and Australian officials, who maintained that their government’s legal advisers had determined the war was justified by Iraq’s failure to comply with U.N. Security Council resolutions. U.S. officials also criticized the timing of the remarks, which came just days before President Bush is due to address the U.N. General Assembly on Tuesday.

“If I had been his adviser, which I wasn’t, I would have advised him not to say it at all and if he was going to say it at all not to say it now. But he did and there’s a difference of opinion,” said John Danforth, U.S. ambassador to the United Nations.