A new independent investigation of abuse allegations at Guantanamo Bay, Cuba (search), "doesn't make sense," Defense Secretary Donald H. Rumsfeld (search) said Sunday.

Some Democratic lawmakers are pushing for an independent commission to look into conditions at the detention center at the U.S. Navy base in Cuba.

An estimated 540 detainees — most of them captured during battles in Afghanistan (search) — are being held at the base.

Last week, the White House rejected the idea of an independent commission, citing 10 major investigations by the Pentagon.

"I think that to go back into all of the things that's already been reviewed by everybody else doesn't make sense," Rumsfeld said on NBC's "Meet the Press" on NBC.

"But that's not a decision for me. That's a decision for the president," he said.

House Minority Leader Nancy Pelosi, D-Calif., has said an independent commission could explore the atmosphere that permitted abuses, how troops were trained, and the length of detentions.

House members of both parties toured the facility on Saturday and noted progress in improving conditions and protecting the rights of detainees. Rep. Sheila Jackson Lee (search), D-Texas, acknowledged improvements but still supported an investigation by an independent commission.

Some detainees have been incarcerated for more than three years without being charged. Rumsfeld defended the detentions by citing the prisoners' alleged deeds.

"These are bad people," Rumsfeld said on "FOX News Sunday."

"These are suicide bombers, these are murderers. This is the 20th hijacker from 9/11 down there. These are people who are out to kill people," he said.

Rumsfeld said U.S. policy calls for humane treatment of the detainees. Any U.S. personnel who have committed wrongdoing there have been punished, he said.

Amnesty International has called the detention center "the gulag of our time," a charge the Bush administration has ridiculed.