Army Staff Sgt. Robert Bales will be charged with 17 counts of murder, assault and a string of other offenses in the massacre of Afghan villagers as they slept, a U.S. official said.

The charges against Bales include 17 counts of murder, six counts of attempted murder and six counts of aggravated assault as well as dereliction of duty and other violations of military law, the official said on condition of anonymity because the charges had not been announced.

The 38-year-old soldier and father of two who lives in Lake Tapps, Washington, will be charged with going on a shooting rampage in two villages near his Southern Afghanistan military post in the early hours of March 11, gunning down nine Afghan children and eight adults and burning some of the victims' bodies.

The charges are to be read to Bales on Friday. And they reflect the change earlier Friday that increased the number of Afghans killed in the shooting spree from 16, which was widely reported for the past week, to 17.

There was initial confusion about the number of dead, hampered to some degree by the fact that some may have been buried before U.S. military officials arrived at the scene of the carnage. Defense officials said Friday that investigators have now determined that there were 17 killed, but they were unable to provide any other details about how the change came about. Six Afghans were wounded in the attack.

Bales' civilian attorney, John Henry Browne, did not immediately respond to telephone and email messages seeking comment on the charges.

Bales is being held in a military prison at Fort Leavenworth in Kansas and faces trial under the Uniform Code of Military Justice.

The killings were yet another blow to U.S.-Afghan relations, following a series of missteps, including the mistaken burning of Qurans, which prompted violent protests and revenge killings of American troops in the war zone.

The brutal shooting rampage also prompted renewed debate in the United States about health care for the troops, who have experienced record suicide rates and high rates of post-traumatic stress and brain injuries during repeated deployments over a decade of the wars in Iraq and Afghanistan.

Bales was on his fourth tour of duty, having served three tours in Iraq, where he suffered a head injury and a foot injury. He was assigned to the 2nd Battalion, 3rd Infantry Regiment of the 3rd Stryker Brigade Combat Team, of the 2nd Infantry Division, which is based at Joint Base Lewis-McChord in Washington state.

Browne has portrayed his client as a patriot, loving father and devoted husband who had been traumatized by a comrade's injury and sent into combat one too many times.

There have been conflicting reports about what exactly Bales saw relating to the comrade's injury. A U.S. defense official said that while it is likely that a soldier from Bales' unit, based in the Panjwai district of Kandahar Province in southern Afghanistan, suffered a leg wound a day or two before the March 11 shootings, there is no evidence that Bales witnessed it or the aftermath, or that it played any role in his alleged actions.

The official spoke on condition of anonymity to discuss an internal review.

Afghan officials have asked the United States for some role in the criminal proceedings, perhaps as observers, and to be kept up to date on the process of the case. The government of Afghan President Hamid Karzai has not demanded that Bales be turned over to the Afghan justice system, although some in the country's parliament did. The Afghans also have urged a fast resolution of the case.

Browne also has said that Bales has some memories from before the incident and some from after, but very little of the time when the military says he went on the shooting spree.

``I'm not putting the war on trial,'' Browne has said, ``but the war is on trial.'' He added: ``If I can help create a discussion about the war, that would be a great way for me to go out.''

Army officials have said Bales was cleared for return to duty after the head injury he suffered in Iraq.

Bales joined the Army in 2001 after a Florida investment business failed and after he had worked with a string of securities operations. Bales and a broker at one company were hit in 2003 with a $1.5 million arbitration ruling after an elderly couple charged that their holdings were decimated.

He also was arrested in 2002 for the drunken assault of a casino security guard, and had to complete an anger management class. There also are reports of a second incident involving alcohol, although Bales was never formally charged.

A sheriff's department report released Thursday says Robert Bales was accused in 2008 in Washington state of shaking hands with a woman, pulling her hand into his crotch and then punching and kicking her boyfriend. It describes Bales as ``extremely intoxicated.''

A message seeking comment from Bales' attorney was not immediately returned. (AP)