Tesla chief executive Elon Musk says he did not intend to accuse a British diver who helped in the Thai cave rescue of paedophilia by branding him a "pedo guy" on Twitter.

Key points: Mr Musk says his use of the phrase "pedo guy" was meant to insult Mr Unsworth's appearance and demeanour, not to accuse him of being a sexual offender

Mr Musk says his use of the phrase "pedo guy" was meant to insult Mr Unsworth's appearance and demeanour, not to accuse him of being a sexual offender Mr Unsworth's lawyer says the claim is offensive and promised an "explosive" response when the matter returned to court

Mr Unsworth's lawyer says the claim is offensive and promised an "explosive" response when the matter returned to court The "pedo guy" tweet came after Mr Unsworth said Mr Musk's offering of a mini submarine to assist in the Thai cave rescue was a PR stunt

The Tesla chief executive is seeking to dismiss a defamation lawsuit brought by Vernon Unsworth over a tweet by Mr Musk last year.

Mr Musk posted the tweet, for which he later apologised, after Mr Unsworth accused him in a CNN interview of grandstanding by offering to help his diving team rescue 12 boys and their soccer coach from a cave in Thailand in July 2018.

Mr Unsworth sued two months later in Los Angeles federal court, saying Mr Musk falsely branded him a paedophile and child rapist.

L Lin Wood, a lawyer for Mr Unsworth, in an interview called his client "a good man whose efforts saved the lives of 13 people", and said he would reply to Mr Musk's court filing discussing the tweet in three weeks.

"I'll keep my powder dry for now, but I can assure you it will be explosive," he said.

He called Mr Musk's motion "as offensive to the truth as was his original tweet".

Elon Musk deleted tweets attacking the diver.

Mr Musk, who grew up in Pretoria, said "pedo guy" was "a common insult used in South Africa when I was growing up".

He said the expression was "synonymous with 'creepy old man'" and used to insult a person's appearance and demeanour.

"I did not intend to accuse Mr Unsworth of engaging in acts of paedophilia," Mr Musk said.

"In response to his insults in the CNN interview, I meant to insult him back by expressing my opinion that he seemed like a creepy old man."

Mr Musk also said his "off the record" August 2018 email to a BuzzFeed News reporter to "stop defending child rapists" was based on an aide's summary of a private investigator's report on Mr Unsworth, and that he did not then know the statement was false.

Mr Unsworth has said he had shared a house in the Thailand countryside with a 40-year-old woman who owned a nail salon.

Mr Unsworth helped in the rescue of a Thai soccer team and their coach from a cave last year. ( AP: Sakchai Lalit )

The dispute arose after Mr Unsworth told CNN that a mini-submarine offered for the rescue from the Tham Luang Nang Non cave by Mr Musk's company SpaceX was a "PR stunt" and that Mr Musk could "stick his submarine where it hurts".

In a related court filing, Mr Musk's lawyers called Mr Unsworth a public figure on matters related to the cave rescue.

They said this required Mr Unsworth to show by clear and convincing evidence that Mr Musk made his statements toward him with "actual malice", a high standard.

Mr Unsworth is seeking compensatory and punitive damages.

A trial is scheduled for December 2.

Mr Musk recently settled a US Securities and Exchange Commission lawsuit over his Twitter use.

Reuters