Two U.S. soldiers have been charged with murdering an Iraqi civilian, raising to four the number of American soldiers from the same unit charged in the past week with killing Iraqis.

The 1st Cavalry Division, which operates in and around Baghdad, named the two soldiers as Staff Sgt. Johnny Horne and Staff Sgt. Cardenas Alban, both from the 1st Battalion of the 41st Infantry Regiment, based at Fort Riley, Kan.

The military said it would give no further details of the case because an investigation had begun.

Last week, two soldiers from the same unit, Sgt. Michael P. Williams and Spec. Brent W. May, were charged with premeditated murder in the deaths of three Iraqi civilians.

On Sunday, the military announced that a U.S. soldier had been sentenced to 25 years in prison for the murder of an Iraqi National Guardsman in May.

Spec. Federico Merida, 21, from Briscoe, N.C., pleaded guilty to murder and to making false official statements during his court-martial, the Army said. In addition to getting 25 years, he was dishonorably discharged and reduced in rank to private, a statement said.

[A Dutch soldier, meanwhile, pleaded not guilty Monday to charges of negligence and excessive use of force in the fatal shooting of an Iraqi civilian, in the first court-martial of a Dutch serviceman in Iraq, the Associated Press reported from Arnhem, Netherlands.]