Updated

SAN JUAN, Puerto Rico (AP) — Two Guantanamo Bay detainees have been transferred to Spain and one to Bulgaria as part of the Obama administration's effort to eventually close the prison at the U.S. military base in Cuba.

The U.S. Defense Department said Tuesday it would not disclose the prisoners' names or any details about them. It says the information is being withheld for security and privacy reasons at the request of the governments of Spain and Bulgaria.

The transfer of the men Monday brings the total of prisoners held at Guantanamo to about 181.

The U.S. has released more than 590 prisoners since opening the prison in early 2002 after the 9/11 attack.