The top military commander in Iraq (search) told Congress on Wednesday that U.S. personnel who have received relatively light punishment in the prisoner abuse scandal may yet face criminal charges.

"We may find that the evidence produced in these investigations not only leads to more courts-martial, but causes us to revisit actions previously taken ... in cases which may have been handled to date by adverse administrative action," said Lt. Gen. Ricardo Sanchez (search).

Sanchez spoke at a Senate Armed Services Committee hearing that examined a wide range of issues, including the abuse at Abu Ghraib prison (search) and prospects for a smooth transfer of political control to an interim Iraqi government on June 30.

Gen. John Abizaid, commander of the U.S. Central Command (search), told senators that the June 30 date "is achievable — but it needs to emerge soon as to who is going to be in charge — what their names are and what they're going to do."

Political factions inside Iraq are jockeying over who should make up that government. The Bush administration has said it is working with a U.N. envoy to develop a list of Iraqis who will be involved.

The hearing unfolded not long after Spc. Jeremy C. Sivits (search) was sentenced in Iraq to a maximum penalty of one year in prison, a reduction in rank and a bad conduct discharge for his role in the abuse at Abu Ghraib.

His was the first court-martial in the wake of the scandal that has shaken the Bush administration and coincided with an erosion in public support for the war.

Sen. John Warner, R-Va., the committee chairman, interrupted the hearing at one point to announce that the Pentagon had discovered the existence of a new computer disk with photos of prisoner abuse. He said lawmakers would be permitted to see the images.

The Pentagon brought other disks to the Capitol last week for lawmakers to see. Members of Congress emerged grim-faced after viewing the images. Lawmakers expressed shock at what they said were scenes of sadism and of prisoners who forced to assume sexually humiliating positions.

Abizaid and Sanchez readily acknowledged that there were problems, such as overcrowding, in the prison system in Iraq. But they insisted there was neither widespread abuse or prisoners nor official countenancing of any mistreatment that did occur.

"How can you explain the culture of abuse that was allowed to develop in a prison system under your ultimate command?" Sen. Robert C. Byrd, D-W.Va. asked Abizaid.

"I don't believe that the culture of abuse existed in my command," he replied.

In addition to Sivits, six enlisted men and women from a reserve military police company based near Cumberland, Md., face charges.

At least six more soldiers have received administrative reprimands. Two have been relieved of their duties; a seventh received a lesser reprimand.

Other investigations are also under way, including one into the military intelligence unit that conducted interrogations at the prison.

Many of those disciplined are officers, and the head of Sivits' brigade, Brig. Gen. Janis L. Karpinski, is the highest-ranking officer who has been admonished.

That was the group that Sanchez referred to when he told the Senate committee that some personnel who have been disciplined administratively may yet face courts-martial.

Abizaid told the committee there have been instances of abuse in Afghanistan (search), although not on the scale of those at Abu Ghraib.

Maj. Gen. Geoffrey Miller, the former commander of the Guantanamo Bay prison who now is in charge of the military's prisons in Iraq, said there were a "few instances of minor abuse" at the Cuban facility where the United States holds suspected Al Qaeda (search) members.

"There was no systemic abuse at Guantanamo at any time," Miller said. He said two or three military personnel received administrative penalties and that one was court-martialed.

The hearing opened as Republicans squabbled about the wisdom of continued sessions on the prisoner abuse.

Rep. Duncan Hunter, R-Calif., the chairman of the House Armed Forces Committee, said Tuesday the hearings were "disserving our military operation" in Iraq by summoning additional commanders to testify.

"I think the Senate has become mesmerized by cameras and I think that's sad," he said.

Warner did not respond directly to Hunter, although the senator said the generals had been in the United States for meetings and had not been recalled from Iraq to testify.

Warner said at the hearing that Congress is a "coequal branch of government" under the Constitution and properly was looking into the abuses.