The US has vigorously rebuffed claims by Saddam Hussein that he has been beaten and tortured by the US.
The ousted Iraqi leader used his war crimes trial in Baghdad to accuse the US of mistreating him while in custody.
Saddam Hussein and seven co-defendants are due back in court on Thursday, to hear more testimony from witnesses.
On Wednesday, men from the Shia village of Dujail described being taken away and tortured by Iraqi security forces.
White House spokesman Scott McClellan called Saddam Hussein's allegations "preposterous".
"Saddam Hussein is being treated the exact opposite of the way his regime treated those he imprisoned and tortured," Mr McClellan said.
A state department spokesman, Sean McCormack, said the allegations were "highly ironic".
"Look, he's been given to grandstanding in this trial, but where the focus should be is on the testimony of those people who were victimised.
"That's what people should be listening to."
Iraq's ex-leader is on trial over the killing of 148 people in a Shia village in 1982. He denies responsibility.
Saddam Hussein sat quietly through most of Wednesday's testimony - graphic accounts of alleged torture by his own regime - before standing to accuse his US captors of ill-treatment.
"I have been beaten on every place of my body, and the signs are all over my body," he told the court.
The sound feed to the television coverage - being seen across Iraq - was cut several times during his outburst, the BBC's Quil Lawrence reports from Baghdad.
This has been seen as an attempt to keep Saddam Hussein from upstaging the testimony of the witnesses, he says.
The prosecution gave little credence to the former president's claim he had been tortured, saying he was being held in an air-conditioned room when some of Baghdad had no power.
Chief prosecutor Jaafar Mousawi said the claims would be investigated and that he would ask for Saddam Hussein to be transferred to Iraqi custody if there was any truth to them.
One US embassy official in Baghdad, Christopher Reid, agreed that all accusations of mistreatment should be investigated.
The allegations were probably made up to ambush the judge, he wrote during a chat session on the White House website.
"I know that the soldiers who guard them have it rougher than they [the defendants] do. Until today, I never heard Saddam make these allegations," he added.
Witnesses speak out
Earlier, two of three witnesses said Saddam Hussein's half-brother Barzan al-Tikriti - a former intelligence chief who is also on trial - had been present when they were tortured.
One described how his entire family of 43 was rounded up and imprisoned.
The witnesses told of intelligence agents shocking people with electricity and pouring melted plastic on people's flesh.
One said he had been tortured three times at intelligence headquarters, then sent to Abu Ghraib prison for over a year before being exiled to the desert for months.
After he was allowed to return home, he was seized afresh by intelligence agents and kept in solitary confinement until he pleaded with them to kill him.
"For God's sake, if you are going to execute me, take me out and execute me!"
After the day's proceedings, the case is expected to be adjourned until mid-January.
The ousted president is expected to face further charges relating to his tenure as Iraqi leader and could be hanged if found guilty.