Continued from page 1

Senior posts are supposed to rotate geographically, but the past five undersecretaries general for management have been American. That is in part because Washington is the organization’s largest single donor.

Officials said that just last week Mr. Annan spoke to U.S. diplomats about finding a successor for Mrs. Bertini.

Mr. Halbwachs is also leaving the United Nations after a long tenure — some 30 years as controller. He told colleagues yesterday that he would accept early retirement.

“His leaving is a real loss,” said one diplomat who worked closely with Mr. Halbwachs. “He won’t be that easy to replace, I fear.”

Other senior posts are vacant or will open up soon.

The head of the U.N. agency that oversees aid to Palestinian refugees, the U.N. Relief and Works Agency, apparently has not yet decided whether to seek a third term. Peter Hansen, of Denmark, has served nine years in the position, incurring the wrath of Israel, the impatience of Arab nations and the distrust of Washington, UNRWA’s biggest donor.

The head of UNICEF, Carol Bellamy, an American, will conclude her second term in April. She is unlikely to seek a third term given Washington’s insistence that no senior official should serve more than two terms.

That is the Bush administration’s rationale for opposing a third term for Mohamed ElBaradei, the Egyptian nuclear scientist who runs the International Atomic Energy Agency in Vienna. Mr. ElBaradei has refused to go along with Washington on two key issues recently, declining to certify that Iran and Saddam Hussein’s Iraq were seeking nuclear weapons.

Also, the U.N. inspector-general’s office, filled for one five-year term that cannot be extended or renewed, will be open in April.

Mr. Annan has said that no senior official should serve in one job for more than a decade. Most U.N. agencies have adopted similar time limits.

The Food and Agriculture Organization is about to adopt a two-term rule, but it is not expected to apply to current head Jacques Diouff, who has served 12 years and is seeking another appointment.