A woman who works as a corporate lawyer with an Alaska energy company has accused U.S. Supreme Court Justice Clarence Thomas of groping her in 1999, a charge he called "preposterous" and untrue.

The woman, Moira Smith, said Thomas grabbed and squeezed her buttocks several times during a dinner party when she was 23 years old in the Falls Church, Virginia home of her boss at the time, the National Law Journal reported on Thursday.

Thomas, 68, joined the high court in 1991 after contentious Senate confirmation hearings involving sexual harassment allegations against him made by another female lawyer, Anita Hill.

Smith, currently vice president and general counsel at Enstar Natural Gas Co in Alaska, released a statement in which she said Thomas "touched me inappropriately and without my consent." Laura Fink, a political consultant in San Diego acting as Smith's spokeswoman, said the National Law Journal's account of the allegations was accurate.

Thomas, in a statement to the National Law Journal, said, "The claim is preposterous and it never happened."

A Supreme Court spokesman declined to comment on Thomas' behalf. Reuters was not able to independently verify Smith's accusations.

The National Law Journal reported that Smith's allegations came to light when she posted an account of the incident on Facebook on Oct. 7 after news broke about Republican presidential candidate Donald Trump's explicit comments recorded in 2005 about groping women.

Several women have since accused Trump of groping and kissing them without their consent. He has denied the claims.

Smith was working at the time of the alleged incident for the Truman Foundation, which provides scholarships to people who hope to pursue public service careers.

"As the mother of a young daughter and son, I am coming forward to show that it is important to stand up for yourself and tell the truth. When powerful men commit sexual assault, they count on their victims keeping it a secret," Smith said in her statement.

The National Law Journal said three of Smith's housemates at the time of the incident recalled her describing Thomas' actions on the night of or the morning after the alleged incident. Beth Frerking, the National Law Journal's editor-in-chief, said the publication stood by the story.

This week marked Thomas' 25th anniversary on the high court after being selected by Republican President George H.W. Bush.

Hill accused Thomas of sexually harassing her when he worked at the U.S. Department of Education and the U.S. Equal Employment Opportunity Commission. Thomas, the court's second black justice, denied the allegations and called the Senate hearings "a high-tech lynching for uppity blacks."

The Senate confirmed him on a 52-48 vote. Since then, Thomas emerged as a unique figure on the court, rarely speaking during oral arguments and plotting his own conservative course on the law.