UNITED NATIONS – One of the biggest power players at the United Nations abruptly announced his retirement yesterday in what may signal the beginning of a Turtle Bay shake-up, just one day after Secretary-General Annan said that the scandals and attacks from outsiders had “cast a shadow” on the institution.

In an announcement that surprised even the U.N. spokesman, Fred Eckhard, who made it at a regular press briefing after a note was passed to him from upstairs, Mr. Annan said that he accepted a request from his chief of staff, Iqbal Riza, to retire “with very mixed emotions.” His retirement will take effect on January 15, Mr. Annan said in the statement. . . .

Mr. Riza, 70, who has been chief of staff since January 1997, is considered the most influential policy adviser to the secretary-general, and many feel he was a leader in a policy that is perceived as adversarial to Washington, especially on issues related to Iraq and Israel. A U.N. insider said Mr. Riza leads a group of advisers who have called on Mr. Annan to take a hard line, urging him to refuse to share information with the congressional oil-for-food investigations.

Are the dominoes falling?