Denver - The Air Force charged three of its cadets with sexual misconduct on Thursday, including one accused of rape, just over a week after the government revealed a rise in reports of sexual assault at military academies.

The three cadets all attended the Air Force Academy in Colorado Springs, Colorado, but were involved in separate incidents over the past 15 months, the military said.

"Sexual misconduct is a particularly egregious offense and we have a zero tolerance policy in the Air Force," Colonel Tamra Rank, vice superintendent of the academy, said in a statement. "We expect the best from our cadets, and do not tolerate unacceptable behaviors."

The charges came after the Department of Defense said last week that U.S. military academies had seen reports of sexual assaults rise sharply to 65 in the last academic year from 41 previously, and announced new policies to help victims.

In September, the U.S. Government Accountability Office had said the military needed greater leadership and oversight to prevent sexual harassment in its ranks.

Rank said that while the three Colorado cases were separate, the men were charged simultaneously because investigations in their cases were recently completed.

Cadet Robert Evenson Jr, who faced the most serious accusations, was charged with rape, unlawful sex acts, engaging in an unprofessional relationship and conduct unbecoming an officer.

An Air Force charging sheet said Evenson raped a female cadet on one occasion and engaged in forced sex acts on other occasions, in three instances using "power or strength or restraint" to prevent escape.

Cadet Kyle Cressy was accused of aggravated sexual assault on a woman while she was "substantially incapacitated." Cadet Stephan Claxton was accused of unbuttoning and unzipping a female cadet's pants while she was incapacitated, the charging sheet said.

He was also accused of underage drinking, abusive sexual contact and several instances of assault, which included an accusation he punched another cadet in the face.

The military did not reveal the ages of the men charged, nor were the women identified although some of them were described as female cadets.

The charges were not the first instance of sexual misconduct accusations involving cadets. In 2003, reports surfaced that dozens of female Air Force Academy cadets had been sexually assaulted by fellow cadets for a decade, but that academy officials ignored or downplayed their complaints.

The fallout from that led to a shake-up in the academy's administration following hearings before Congress.

The next step in the three latest cases is an Article 32 hearing, which is the military equivalent of a civilian grand jury, the Air Force said.

The accusations against the cadets are deemed by the military as "preferred charges," and the hearing will determine which if any charges are finally leveled against them and whether to move forward with court martial proceedings, Air Force Academy spokesman Lieutenant Colonel John Bryan said.

All three cases will be dealt with separately, Rank said.