"They were tagged as security detainees and they could not simply be released," she said.
The military said he was a "security detainee" but would not elaborate.
"Since the end of August, we have released approximately 2,800 security detainees."
Mr. Rumsfeld said he could not explain what she meant by "security detainees."
"He is currently detained and will be processed as any other security detainee," the statement said.
During this election, security detainees held by coalition forces and the Ministry of Interior were given the opportunity to vote.
On 19 April 2005, a 51-year-old male security detainee at Camp Bucca died of natural causes.
On 5 October 2005, a 43-year-old male security detainee died of a heart attack.
On 23 October 2005, a 73-year-old male security detainee died of natural causes at Camp Bucca.
All are classified as security detainees, American military officials say.