U.S. president-elect Barack Obama is preparing to issue an executive order his first week in office — and perhaps his first day — to close the U.S. military prison at Guantanamo Bay, according to two presidential transition team advisers.

It's unlikely the detention facility at the navy base in Cuba will be closed anytime soon. In an interview last weekend, Obama said it would be "a challenge" to close it even within the first 100 days of his administration.

But the order, which one adviser said could be issued as early as Jan. 20 — the day Obama is to be sworn into office — would start the process of deciding what to do with the estimated 250 people being held at Guantanamo. Most are accused of links to al-Qaeda or the Taliban; the majority has not been charged with a crime.

The Guantanamo directive would be one of a series of executive orders Obama is planning to issue shortly after he takes office, according to the two advisers. Also expected is an executive order about certain interrogation methods, but details were not immediately available Monday.

The advisers spoke on condition of anonymity because they were not authorized to speak publicly about the orders that have not yet been finalized.

Obama transition team spokeswoman Brooke Anderson declined comment Monday.

The two advisers said the executive order will direct the new administration to look at each of the cases of the Guantanamo detainees to see whether they can be released or if they should still be held — and if so, where.