WASHINGTON — The Army general who conducted a major investigation into U.S. mistreatment of Iraqi prisoners told a Senate panel Tuesday that military police acted "of their own volition" at a facility under the control of military intelligence officers.

His statement was contradicted by a senior civilian Defense Department official who told the Armed Services Committee that military intelligence did not have authority over the military police operations.

The differing accounts by the two officials muddled an already unclear picture of the lines of command at Abu Ghraib prison near Baghdad. The distinction could prove significant because soldiers accused of the abuses reportedly have said that they were following orders from intelligence personnel.

Maj. Gen. Antonio Taguba told lawmakers that the abuse suffered by some Iraqi detainees at the hands of soldiers was the result of poor leadership, lack of discipline and "no training whatsoever." He also agreed with Pentagon assertions that only a few individuals were involved and that the scandal does not signal a systemic problem in the military.

"We did not find any evidence of a policy or a direct order given to these soldiers to conduct what they did," Taguba said. "I believe that they did it on their own volition."

Taguba (pronounced tah-GOO-bah) said that the military leadership "from the brigade commander on down" shared the blame.

But confusion continued as to whether the soldiers were acting on orders from intelligence officials. At issue is a Nov. 19, 2003, order that placed the prison under the tactical control of the 205th Military Intelligence Brigade.

Stephen Cambone, undersecretary of defense for intelligence, told lawmakers that the order did not give the military intelligence commander authority over military police operations at the prison. Instead, it applied to control over such matters as security, force protection and living conditions for the troops, he said.

But Taguba had a different interpretation of the order, saying that it gave the military intelligence commander control of all units at Abu Ghraib, including the MPs operations.

An investigation into the involvement of military intelligence is among many that are under way. The senators also heard testimony Tuesday that Central Intelligence Agency officers may also have been involved in the abuses.

Recently published photos depicting prisoners naked and in humiliating and sexual situations have caused worldwide outrage and embarrassed the military. Seven soldiers have been criminally charged, and the first court martial is scheduled for May 19.