Lt. Cmdr. Nick Balice of US Central Command in Tampa, Florida said on Saturday an investigation was underway into alleged mistreatment of some prisoners by some soldiers.
The abuse investigation centred on events that occurred in mid-May at Camp Bucca, where 7,000 prisoners of war were detained during the war to oust Iraqi President Saddam Hussein.
That camp, near the southeastern port of Umm Qasr, is the largest US-run POW detention centre in Iraq.
"Four soldiers have been charged based on allegations of mistreatment," said Balice, who declined to identify the soldiers or to detail the allegations.
A military trial was expected for the four, Balice said.
Complaints of abuse
The four were the first US soldiers to face charges of abusing prisoners during the US-led war against Iraq.
Some Iraqi prisoners who were released have complained of maltreatment at the hands of their US guards.
And the London-based human rights group Amnesty International said in June it has gathered evidence which shows the US violated international law by subjecting Iraqi prisoners to "cruel, inhuman or degrading" conditions.
Three Iraqi prisoners of war have died in camps run by American and British troops.
The occupation authorities have said they are investigating the circumstances behind their deaths.