WASHINGTON — Sexual assaults in the military are a growing epidemic across the services, and thousands of victims still are unwilling to come forward despite a slew of new oversight and assistance programs, according to Pentagon documents.

Troubling new numbers estimate that up to 26,000 military members may have been sexually assaulted last year, according to survey results released against a backdrop of scandals, including an ongoing investigation into more than 30 Air Force instructors for assaults on trainees at a Texas base.

The report comes just days after the Air Force’s head of sexual assault prevention was arrested last weekend on charges of groping a woman in a Virginia parking lot. And it follows a heated debate over whether commanders should be stripped of the authority to overturn military jury verdicts, such as one officer did in a recent sexual assault conviction.

President Barack Obama delivered a sharp rebuke Tuesday, saying he has no tolerance for the problem, and he said he talked to Defense Secretary Chuck Hagel about it. He said that any military member found guilty of sexual assault should be held accountable, prosecuted and fired.

“I don’t want just more speeches or awareness programs or training, or ultimately folks look the other way,” he said. “We’re going to have to not just step up our game, we have to exponentially step up our game to go after this hard.”

The Associated Press obtained documents and memos related to a new Pentagon report. The documents show that the number of sexual assaults reported by members of the military rose 6 percent to 3,374 in 2012. A survey of personnel who were not required to reveal their identities showed the number of service members actually assaulted could be as many as 26,000, but they did not report the incidents, officials said Tuesday.

There were an estimated 19,000 assaults in 2011.

The statistics highlight the dismal results that military leaders have achieved in their drive to change the culture within the ranks, even as the services redoubled efforts to launch new programs to assist the victims, encourage reporting and increase commanders’ vigilance.

Hagel ordered a series of steps and reviews to increase officers’ accountability for what happens under their commands, and to inspect workstations for objectionable materials, according to memos and documents obtained by the AP.