Abdulmutallab, the Nigerian national convicted of attempting to detonate explosives hidden in his underwear on a Christmas Day 2009 flight from Amsterdam, Netherlands, to Detroit, joined other al-Qaida affiliates at the "Alcatraz of the Rockies" Wednesday, The Detroit News reported.
A federal Bureau of Prisons spokesman declined to say why Abdulmutallab, 25, was moved to the super-maximum prison, the newspaper said.
"We wouldn't comment about why any inmate is moved from one status to another," prisons spokesman Edmond Ross told the newspaper Thursday. "Every individual is reviewed, and they are placed in the appropriate secured facility."
The supermax facility in Florence, Colo., houses 430 inmates -- including Unabomber Ted Kaczynski and Oklahoma City bombing plotter Terry Nichols -- some of whom are locked in their cells for 23 hours a day.
Abdulmutallab, who is serving four life terms, likely will not be allowed to communicate with inmates or visitors.