The Pentagon is preparing to launch an investigation into its procedures in light of the Fort Hood shooting rampage, officials said Tuesday.

Maj. Nidal Malik Hasan has been charged with 13 counts of murder in connection with a shooting at Fort Hood, Texas. (Uniformed Services University of the Health Sciences/Associated Press)The probe is still in the planning stages, but would be a broad examination of all corners of the Pentagon and would go beyond the particulars of army psychiatrist Nidal Malik Hasan, Pentagon spokesman Geoff Morrell said.

Hasan, a 39-year-old army major, is accused of killing 13 people in the Nov. 5 shooting spree at the sprawling Texas army base.

He has been charged with 13 counts of premeditated murder in the attack, which also left 29 people wounded.

The army has also been preparing to launch its own internal probe, but the Pentagon review could supersede that investigation.

"This is larger than the army. There are issues that need to be looked at department-wide, and the focus at this point is trying to figure out some of those questions," Morrell said.

The investigation will also look at how U.S. military services keep a watch on potential problems in their ranks.

Peter Chiarelli, the U.S. army's vice-chief of staff, said officials fear more people like Hasan may be undetected inside the armed forces.

"I think we always have to be concerned about that," Chiarelli said as he outlined separate efforts to curb rising suicide rates in the army. The service has been the combat force most affected by the stress of fighting two wars.

Any new review would have to be careful not to interfere with the continuing criminal investigation, defence officials said.