McSally, 52, who spent 26 years in the Air Force and commanded a fighter squadron, revealed the attack in emotional remarks during a Senate subcommittee hearing on sexual assault in the military.

"I am also a military sexual assault survivor but unlike so many brave survivors I didn't report being sexually assaulted," McSally said.

"Like so many women and men I didn't trust the system at the time," she said. "I blame myself. I was ashamed and confused. And I thought I was strong but felt powerless.

"The perpetrators abused their position of power in profound ways," the first-term Republican senator said. "And in one case I was preyed upon and then raped by a superior officer."

McSally, who served in the Air Force until 2010 and retired with the rank of colonel, said she kept quiet about the assault for many years.

"But later in my career, as the military grappled with scandals and their wholly inadequate responses, I felt the need to let some people know -- I too was a survivor," she said.

McSally said she considered leaving the military at one point.

"I almost separated from the Air Force at 18 years over my despair," she said. "Like many victims I felt the system was raping me all over again.

"But I didn't quit," she said. "I decided to stay and continue to serve and fight and lead, to be a voice from within the ranks for women and then in the House and now in the Senate."

- Educate commanders -

McSally said military commanders needed to be better educated in handling sexual assault cases.

"We've come a long way to stop military sexual assault but we still have a long way to go," she said.

"I share the disgust at the failures of the military system and the many commanders who failed in their responsibilities," the senator said.

"We must educate, select and then further educate commanders who want to do the right thing but who are naive to the realities of sexual assault," she said.

"We must ensure that all commanders are trained and empowered to take legal action, prosecute fairly and rid perpetrators from our ranks."

McSally lost a close race in November to Democrat Kyrsten Sinema but was later appointed by the Arizona governor to fill the seat once held by John McCain, who died in August.

She is expected to contend for the Senate again in 2020 and may face a potentially tough race against former astronaut and US Navy veteran Mark Kelly, who is seeking the Democratic nomination.

Republican Senator Joni Ernst of Iowa, who is also a military veteran, revealed earlier this year that she had been raped while in college.

In a report released in May 2018, the Pentagon said the number of sexual assault cases reported by service members rose by about 10 percent in fiscal 2017.

It said the Pentagon received 6,769 reports of sexual assault involving service members as either victims or subjects of criminal investigation.