Music superstar Taylor Swift told a US court Thursday of her shock as she realized she was being groped during a photo opportunity in Colorado, as she faced the former DJ she accuses of assaulting her.

Swift, 27, said there was no doubt in her mind the radio personality she was being photographed with ahead of a Denver concert in 2013 reached under her skirt and fondled her buttocks.

"It was a definite grab... a very long grab," Swift testified in a Denver federal court. She declined to speculate how long the incident lasted.

"He stayed latched on to my bare ass cheek as I lurched away from him. (His hand) didn't let go," she told the jury.

Swift was called as a witness by the attorney representing David Mueller, the former Denver radio host accused of groping her during the photo session.

"It was a very shocking thing. I had never dealt with something like this before," Swift said.

Mueller, 55, is suing Swift, alleging she and her team slandered him by telling his employer about the incident, resulting in his firing.

She is counter-suing, alleging she was sexually assaulted.

"Someone could have concluded it appeared she was trying to get away from me," David Mueller testified Wednesday when shown a picture taken during the alleged assault.

The photo of Swift, Mueller and his girlfriend shows the morning show host on radio station KYGO with his hand behind the singer's rear end.

- '3-D recollection' -

Mueller claims his knuckles may have touched her ribs, well above where his arm is shown. But he admitted he did not know for sure where his hand was because he was concentrating on the photographer.

Swift, who was 23 at the time, did not file a police report. Her mother, Andrea Swift, testified Wednesday that the singer's management wanted to keep the matter out of the public eye.

Swift, who wore a short-sleeved floral print dress, was in combative form as she was questioned for around an hour, occasionally rebuking Mueller's attorney for his line of inquiry.

"I'm not going to allow you or your client to say I am to blame," she told him at one point.

She also rejected Mueller's contention that he may have touched her somewhere less inappropriate.

"He did not touch my hand. He did not touch my arm. He did not touch my rib. He touched my bare ass," Swift said, adding that she had a "3-D recollection" of what had transpired.

She dismissed attempts to dissuade her from her story and rejected the suggestion that she had continued greeting guests for as long as 30 minutes after the alleged assault, as if nothing had happened.

"This is a fact. This is what happened to me. I knew when it happened," she said.

Swift's assistants testified in depositions that as soon as the photo session ended, the singer told everyone in the room about the incident. They described her as being uncomfortable and visibly upset.

Source: AFP