After viewing them on Wednesday in a presentation organized by the Pentagon at Capitol Hill, members said the photos contained disturbing images of torture and humiliation.
Some top Republicans urged the pictures not to be released publicly, saying they could endanger US forces overseas.
"I would state, though, from at least my perspective, that what we saw is appalling," said Senate Majority Leader Bill Frist.
"There were some awful scenes. It felt like you were descending into one of the wings of hell and sadly it was our own creation," said Senator Richard Durbin.
Senators and members of the House of Representatives had a chance to look at more than 1,200 images in separate secure rooms during the presentation.
Republican Jane Harman said the new pictures showed "cruel and sadistic torture."
"I expected that these pictures would be very hard on the stomach lining and it was significantly worse than anything that I had anticipated" said Senator Ron Wyden. "Take the worst case and multiply it several times over."
"There were some awful scenes. It felt like you were descending into one of the wings of hell and sadly it was our own creation"
Senator Richard Durbin
Some photos showed military dogs snarling at cowering prisoners while others depicted Iraqi women prisoners being forced to disrobe.
"There were several pictures of Iraqi women who were disrobed or putting their shirts up. They were not smiling in the pictures, that’s for sure," said Ben Nighthorse Campbell after the viewing.
Rumsfeld defends methods
A few hours before the pictures were screened, US Defence Secretary Donald Rumsfeld defended military interrogation techniques, rejecting complaints that they violate international rules and may endanger Americans taken prisoner.
Rumsfeld told a Senate committee hearing that Pentagon lawyers had approved methods such as sleep deprivation and dietary changes as well as rules permitting guards to make prisoners assume stressful positions.
But Senator Durbin said some of the approved techniques "go far beyond the Geneva Convention," a reference to international rules governing the treatment of prisoners of war.
The US military meanwhile announced that two more soldiers would face court martial for abusing Iraqi prisoners.
Staff Sgt. Ivan "Chip" Frederick and Sgt. Javal Davis, each face five charges, ranging from conspiracy to maltreat detainees, dereliction of duty and failing to protect detainees from abuse.
Frederick has also been charged with wrongfully committing an indecent act by watching detainees commit a sexual act.