WASHINGTON (CNN) -- Preliminary intelligence assessments show more than 14 percent of detainees released from Guantanamo Bay have returned or are suspected of having returned to terrorism activities, an administration official with knowledge of the Defense Department's information said.
A guard talks with a detainee at Guantanamo Bay, Cuba, earlier this year.
That number, which reflects data through the beginning of 2009, has gone up slightly from statistics compiled through the end of 2008, when the recidivism rate was considered to be 11 percent, according to the administration official. It had been at 7 percent in earlier years, but the Pentagon has not disclosed what time frame that encompasses.
The official emphasized the latest data is still being verified within the military intelligence community, but it appears likely to show that the rate of recidivism has reached more than 14 percent.
As of May 15, approximately 540 detainees had been transferred to other countries, according to the Justice Department. Some were detained in their home countries, but others have since been released. Two-hundred-forty detainees are still held in the U.S. naval base at Guantanamo Bay, Cuba.
Earlier this year, the Pentagon reported that 11 percent of detainees released and returned to their home countries were either "confirmed or suspected" of returning to the 'battlefield," the official said. The official emphasized that while the previous report was a more formal assessment, this most recent information is considered a "not fully vetted" assessment of the increase.
"What's clear is we are not seeing recidivism on the decline," the source said.
The latest publicly released information came in January, when Pentagon spokesman Geoff Morell said 62 former Guantanamo detainees may have returned to terrorism or military activity. That number included 18 who had been directly tied to an attack or attacks and 43 who were suspected of such action, Pentagon officials said at the time. The Pentagon never publicly released the full report.
The administration official said a report could be released shortly with numbers through December 2008, now that news organizations have filed Freedom of Information Act requests for it. It's not clear if the most recent unvetted data would be released at that time.
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