FARGO - University of North Dakota athletic director Tom Buning is taking a leave of absence, school officials say, but they refuse to say why.

Buning's duties will be handled by other members of the current athletic department staff, UND spokesman Peter Johnson said Monday. He said no other details would be released.

Calls to Buning were not returned.

Buning, 47, was hired in June 2005, after four years as associate athletic director at Army. He's an Army lieutenant colonel and a 1981 West Point graduate.

Members of the school's athletic department were told about his leave of absence in a letter from Phil Harmeson, a UND vice president in charge of athletics. Harmeson wrote that "a plan will be announced shortly to reallocate his (Buning's) duties and responsibilities."

Harmeson said he would not comment beyond the letter, which thanked the athletic department staff for cooperation and support.

Todd Sequin, president of the Fargo Sioux booster club, said he was baffled by the announcement.

"I don't know the reasons for it," Sequin said. "For the most part, from my perspective, I've never had any problems with what's going on in the athletic department."

Buning's leave comes at a crucial time. UND is moving from NCAA Division II athletics to Division I, beginning in the next school year, and there have been rumblings about how the move is progressing. A consulting firm said UND's athletic expenses may double during its five-year transition.

Buning was hired after school officials interviewed former UND Alumni and Foundation development officer Rob Bollinger, Gustavus Adolphus athletic director Al Molde and Lynn University (Fla.) athletic director John McCarthy. Bollinger left UND last year to become executive director for university advan-cement at Bemidji State.

UND officials cited Buning's experience in budgets and fundraising when he was hired. While at Army, Buning had worked on a $240 million plan for upgrading facilities and a fundraising campaign that brought in more than $100 million.

, UND officials said.

Buning replaced Roger Thomas, who resigned the athletic director job to become commissioner of the North Central Conference. The NCC is disbanding after this year.