Business Insider reported on Thursday that Musk‘s SpaceX paid $250,000 in 2018 to settle a sexual harassment claim from an unnamed private jet flight attendant who accused Musk of exposing himself to her.

The article quoted an anonymous person who said she was a friend of the flight attendant. The friend had provided a statement as part of the private settlement process, according to the article.

“I have a challenge to this liar who claims their friend saw me ‘exposed’ – describe just one thing, anything at all (scars, tattoos, …) that isn’t known by the public. She won’t be able to do so, because it never happened,” Musk tweeted late on Thursday.

Reuters was not able to verify the Business Insider account.

Musk and SpaceX did not respond to Reuters requests for comment on the Business Insider story or on Musk‘s tweets.

In a statement to Reuters on Friday, Business Insider said: “We stand by our story which is based on documents and interviews and which speaks for itself.”

Business Insider quoted the friend of the flight attendant as saying that in addition to allegedly exposing himself, Musk rubbed the flight attendant’s thigh and offered to buy her a horse if she would “do more” during an in-flight massage.

The flight attendant came to believe that her refusal to accept Musk‘s proposal had hurt her opportunities to work at SpaceX and prompted her to hire a lawyer in 2018, according to Business Insider.

The rocket company made the settlement out of court and included a nondisclosure agreement that prevented the flight attendant from speaking about it, Business Insider said. The news site did not name the friend or the flight attendant.

Musk, who is also chief executive of Tesla Inc TSLA.O and is in the midst of a contentious effort to buy Twitter Inc TWTR.N, said on Wednesday that he would vote Republican instead of Democrat, predicting a “dirty tricks campaign against me” would follow.

In the Business Insider article, Musk was quoted as saying the flight attendant’s story was a “politically motivated hit piece” and that there was “a lot more to this story.”

On Thursday evening, Musk first tweeted: “The attacks against me should be viewed through a political lens – this is their standard (despicable) playbook – but nothing will deter me from fighting for a good future and your right to free speech.”

In the initial tweet, he did not specifically mention the allegations in the Business Insider article.

“And, for the record, those wild accusations are utterly untrue,” Musk added in another tweet.

He also tweeted that the article was meant to interfere with the Twitter acquisition.