Gen Jeffery Sinclair is believed to be the highest-ranking military member to be prosecuted for sex crimes. Photo: BBC

The unidentified accuser spoke after opening arguments in a military trial at Fort Bragg, North Carolina, against Brig Gen Jeffrey Sinclair, 51.

Defence lawyers said the general was the victim of an infatuated woman and a prosecution under political pressure.

The Pentagon has been pledging to stamp out an epidemic of sexual misconduct.

In two other cases to emerge on Friday:

• A sergeant from Fort Hood, Texas, Gregory McQueen - who was in charge of sexual assault and harassment prevention at the base - was charged with setting up a prostitution ring involving female soldiers
• A West Point military academy sergeant, Michael McClendon, admitted secretly photographing and videotaping female cadets, some while they were undressed

But the case of Gen Sinclair is believed to be the highest-ranking US military prosecution to date.

He already faces a sentence of up to 15 years after admitting on Thursday to adultery and other charges deemed illegal in the military.

The former deputy commander of the elite 82nd Airborne Division could be sentenced to life in prison if convicted of sexual assault.

'Sexually explicit texts'

In Friday's opening statements, Army prosecutor Col Robert Stelle said Gen Sinclair had used his authority to intimidate a female officer into sexual acts.

The female captain, who has been granted anonymity, testified that Gen Sinclair twice ended arguments about their relationship by forcing her to perform oral sex on him.

She said she "knew it was wrong" when they began their three-year affair. But she said she thought Gen Sinclair's wife knew about their relationship until he told her that she must never find out.

"He told me that if I ever told her or anyone else about he and I, he would kill me and then he would kill my family," she said, sobbing on the witness stand.

"And he would do it in a way no-one would ever know."

But Gen Sinclair's lawyer, Ellen Brotman, read excerpts from the captain's diary, in which she expressed desire for him even after he allegedly threatened violence against her loved ones.

"I'm so in love with him," Ms Brotman read from the diary. "I do know that I love him incredibly... I love him almost unconditionally."

The only fear she expressed, Ms Brotman said, was that he might still love his wife.

Gen Sinclair and his accuser also exchanged thousands of often sexually explicit text messages, even after he tried to end their relationship, said the defence.

On Thursday, a bill that would have stripped military commanders of the authority to decide whether to prosecute rapes and other serious crimes failed to progress in the US Senate.

Lawmakers instead voted to move forward a more moderate measure.