(Reuters) - The military will ramp up efforts to combat sexual assault in the ranks, a crime the secretary of defense decried as a "stain" on the honor of troops and one the Pentagon suspects is vastly underreported.

Speaking to reporters at the Pentagon, Secretary of Defense Leon Panetta said the military received 3,191 reports of sexual assault in fiscal 2011, up slightly from 3,158 the year before. But this is "a very underreported crime," he said, and officials estimate the true number is closer to 19,000 assaults.

Sexual assault has "no place" in the military, Panetta said, according to a Pentagon transcript of the briefing.

"It is an affront to the basic American values we defend, and it is a stain on the good honor of the great majority of our troops and their -- and our families," Panetta said.

Earlier this month, the Air Force charged three cadets in Colorado with sex crimes, including one man accused of raping a female cadet while he physically prevented her from escape.

The Department of Defense late in December released a report that said the number of reports of sexual assaults at military academies rose sharply to 65 in the previous academic year, from 41 previously.

Among the U.S. military more broadly, the number of assaults in the four years prior to 2011 has ranged from a low of 2,688 in 2007 to a high of 3,230 in 2009, according to Defense Department data.

On Wednesday, Panetta outlined a number of steps the Department of Defense will take to deal with the problem.

Those include establishing a sexual assault advocate certification program for its response coordinators and victims advocates, Panetta said.

That will ensure victims of sexual assault "receive the best care" from trained and credentialed professionals, he said.

The military also will offer support to the spouses and adult dependants of sexual assault victims, and for the first time those people will be able to file confidential reports, Panetta said.

Panetta said he is increasing funding for investigators and judge advocates to receive specialized training to deal with sexual assault cases. And an integrated data system bringing together information from different branches of the military will be established to better track assaults, he said.

Late last year, the Pentagon announced service members who report being a victim of sexual assault would be allowed to quickly transfer from their unit to protect them from harassment, and gain distance from any accused perpetrator.

The Pentagon's recent actions to deal with sexual assault came after the U.S. Government Accountability Office said in a report in September that the military needed greater leadership and oversight to prevent sexual harassment in its ranks.

(Reporting By Alex Dobuzinskis; editing by Dan Burns)

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