Dozens of universities and colleges across the United States are facing investigation for the way they handle sexual abuse allegations made by students.

For the first time, the US Education Department revealed a list of 55 institutions under investigation on Thursday, as the administration sought to bring more openness to the issue of sexual violence on and around the country's campuses.

The schools range from public universities, including Ohio State University, the University of California, Berkeley University and Arizona State University, to private ones including Knox College in Illinois, Swarthmore College in Pennsylvania and Catholic University of America in the District of Columbia.

Ivy League schools including Harvard, Princeton and Dartmouth are also on the list.

The government emphasised the list was about investigations of complaints, not judgements. Education Secretary Arne Duncan said there was "absolutely zero presumption'' of guilt.

Few details of individual cases are known. Establishments on the list, for the most part, were unwilling to talk about specific incidents, Associated Press news agency reported.

Military assaults increase

Separately on Thursday, the US Secretary of Defence reported that sexual assaults in the military increased by 50 percent last year. Officials welcomed the news as a sign that victims were more confident their attackers will be prosecuted.

Defence Secretary Chuck Hagel called the increase in reported sexual assaults - from 3,374 to to 5,061 - "unprecedented".

He announced six new directives to expand the fight against sexual assault, including an alcohol policy review and an effort to encourage reporting by male victims. Men are thought to represent about half of the victims of military sexual assault but comprise only 14 percent of the reports that were investigated.

"We believe victims are growing more confident in our system," Hagel told a Pentagon news conference. "Because these crimes are underreported, we took steps to increase reporting and that's what we're seeing."

Critics said the Pentagon's numbers on increased reporting demonstrated little improvement in the proportion of cases going to trial or the percentage of convictions.

A total of 484 cases went to trial in the 2013 fiscal year that ended on September 30 and 370 people were convicted of an offence, the report said. That compared with 302 trials the previous year and 238 convictions.

Source: Agencies