Elon Musk’s lawyer demanded a British cave diver apologise for saying the billionaire’s offer to provide a mini-submarine to rescue 12 boys and their football coach from a flooded cave in Thailand was a “PR stunt”.

Diver Vernon Unsworth is suing the Tesla and SpaceX chief for calling him a “pedo guy” on Twitter, with no evidence.

Mr Unsworth refused to apologise for his comments in a CNN interview in which he said the offer was a “PR stunt” and the entrepreneur could “stick his submarine where it hurts”.

“My insult was to the tube [mini-submarine] and not to Mr Musk personally,” Mr Unsworth said while being cross-examined by Bill Price, one of Musk’s lawyers, on Friday.

“I’m not sure how I need to apologise. It was my opinion at the time and I stand by that opinion.”

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Mr Unsworth’s lawsuit focuses on three of Musk’s tweets on 15 July 2018, sent five days after the diver helped in the Thai cave rescue.

Musk’s first tweet questioned Unsworth’s role in the rescue, while the second said, “Sorry pedo guy, you really did ask for it.” The third tweet, in response to a follower who asked Musk about the second tweet, said: “Bet ya a signed dollar it’s true.”

Mr Unsworth, 64, claimed the tweets harmed his reputation by branding him a paedophile and a liar, and said on Wednesday they left him “humiliated, ashamed, dirtied”.

Courtroom sketch of Elon Musk during the trial (Mona Shafer Edwards/Reuters) (Mona Shafer Edwards/REUTERS)

Musk, 48, who was questioned throughout the afternoon on Tuesday by Mr Unsworth’s lawyer, apologised to the diver on Wednesday and suggested to jurors the stress of working 80 to 100 hours a week during a challenging period for Tesla contributed to the outburst.

On Thursday Musk’s lawyers tried to weaken the defamation argument, suggesting Mr Unsworth’s reputation was unsullied and that he even tried to profit from his role in the rescue, which won him plaudits from the Thai and British governments.

Asked if there was talk of his being a paedophile at a 10 Downing Street event where he stood next to then prime minister Theresa May, Mr Unsworth said: “Not that I recall.”

Mr Unsworth’s legal team called expert witness Jim Jansen, who said the Musk tweets were disseminated widely in the news media – appearing in 490 English language articles in 33 countries.

Judges were expected to begin deliberating in Los Angeles on Friday after both men deliver closing statements.

The three-man, five-woman US District Court jury will be asked to decide by unanimous vote if Musk defamed Mr Unsworth, and if so, how much he must pay in damages.

To win, Mr Unsworth must prove Musk was negligent in publishing a falsehood that clearly identified him and caused him harm.