A megachurch pastor in Tennessee received a standing ovation from his Memphis congregation after admitting to and apologising for a previous "sexual incident" with a teenage girl.

Highpoint Church pastor Andy Savage's confession comes on the heels of accusation from Jules Woodson, who claimed the church leader sexually assaulted her decades ago while he was a youth minister at Woodlands Parkway Baptist Church in Texas.

Woodson, who was 17 at the time of the alleged assault, said she was without a ride after spending the evening with friends at the church in the spring of 1998. She said Savage offered to drive her home, but instead drove her to a wooded area where he assaulted her.

"Suddenly Andy unzipped his pants and pulled out his penis. He asked me to suck it. I was scared embarrassed, but I did it," she wrote on Watch Keep. "I remember thinking this must mean that Andy loved me. He then asked me to unbutton my shirt. I did.

"He started touching me over my bra and then lifted my bra up and began touching my breasts."

Woodson recalled that Savage suddenly ran out of the car and fell to his knee, pleading for forgiveness and begging her not tell anyone.

"I remember him pleading, while he was on his knees with his hands up on his head, 'Oh my god, oh my god. What have I done? Oh my god, I'm so sorry. You can't tell anyone Jules, please. You have to take this to the grave with you,'" she wrote.

Woodson, who said she was left feeling manipulated and ashamed, discussed the incident with church leadership but police were never told.

Savage commented on the "sexual incident" that he believed had been "dealt with in Texas" over the weekend in a speech that was live streamed on the church's YouTube channel.

"Until now, I did not know there was unfinished business with Jules," he said. "Jules, I am deeply sorry for my actions 20 years ago. I remain committed to cooperate with you toward forgiveness and healing."

Chris Conlee, the lead pastor at Highpoint Church, said he was one of those "hurt by the ripple effect of the consequences of that sin" but maintained he stood by Savage's side. In an official statement, Conlee said the assault was "not new to me or our leadership" and described Savage as one of his "closest friends and partner in ministry".

In an interview with The New York Times, Woodson said the church's idea and its response to Savage was "disgusting". She also said she had spoken to a detective in Texas, although it is unclear whether a statue of limitations would be in effect.