A British caver who was labeled "pedo guy" by Tesla co-founder Elon Musk said on Wednesday he felt "humiliated" and "dirtied" by the tech billionaire's accusation, and that it amounted to "a life sentence."

British cave diver Vern Unsworth arrives at US District Court in Los Angeles, California on Tuesday, with his attorneys L.Lin Wood (right) and and Mark Stephen (left) during the defamation trial in the case of Tesla's co-founder and CEO Elon Musk, who is being sued for defamation by Vern Unsworth, claiming he called him a pedophile in a tweet. Photo: AFP

Speaking on the second day of a trial in Los Angeles federal court to determine whether Musk's comment constituted defamation, Vernon Unsworth said the entrepreneur's tweet referring to him as "pedo guy" had branded him as a pedophile.

"It's disgusting," Unsworth told the court, his voice quivering. "I feel humiliated, shamed, dirtied."

"Effectively from day one, I was given a life sentence without parole," Unsworth, who helped rescue youth soccer players trapped in a cave in Thailand, told the court.

He said Musk's Twitter rant had resulted in his name being associated with pedophilia.

"Sometimes I feel very vulnerable, very isolated," he said. "I deal with it on my own, I bottle it up."

Musk's highly-publicized row with Unsworth erupted in July 2018 after the British caver dismissed the entrepreneur's proposal to build a mini-submarine to rescue the boys stuck in the cave as a "PR stunt."

He also said that Musk could "stick his submarine where it hurts."

Attorneys for both sides in court have been going over the meaning of the term "pedo guy," which Musk claims was a common insult in South Africa, where he grew up, and meant nothing more than "creepy old man."

"Pedo guy [means] creepy old guy" in South Africa, Musk's attorney Alex Spiro said.

The 48-year-old tech tycoon insisted during two days of testimony that he was just reacting to Unsworth's "unprovoked" comments about him when he published the tweet.

Musk also referred to Unsworth in email messages as a "child rapist."

He apologized to Unsworth several times during his testimony and insisted his "pedo guy" tweet did not mean he was accusing the caver of being a pedophile.

"Pedo guy is more flippant than pedo, especially in the context I used in the tweet," Musk told the court Wednesday. "It's obviously an insult, no one interpreted it as meaning he was actually a pedophile."

As an example, he added, calling someone "motherfucker doesn't mean incest."

The trial, which began Tuesday and is expected to last through Friday, hinges on whether Musk's tweet could have been interpreted by a reasonable person as accusing Unsworth of pedophilia.

Unsworth, who lives in Britain and Thailand, is seeking unspecified damages for pain, suffering and emotional distress.

His testimony was set to continue on Thursday.