LOS ANGELES (REUTERS) - Elon Musk said he was overworked when he called a British diver and cave explorer a"pedo guy" in a tweet to his millions of followers, as the Tesla chief executive defended himself on Wednesday (Dec 4) at his defamation hearing.

In his second day of testimony in Los Angeles federal court, Musk again expressed regret for the tweet and other comments criticising the plaintiff Vernon Unsworth, and said he had "absolutely not" been accusing him of pedophilia.

Under questioning from his lawyer Alex Spiro, Musk said it took him "minutes" to write his tweets, amid a "very extreme" 80 to 100 hours a week schedule running Tesla, which makes electric cars, and the SpaceX rocket company.

"I wouldn't recommend it," Musk said about his schedule.

Musk's "pedo guy" tweet is one of three tweets that Unsworth has said defamed him and harmed his reputation. He is seeking unspecified damages.

Unsworth had led a successful rescue of 12 boys and their soccer coach from a flooded cave in Thailand, which was completed on July 10, 2018.

Three days later, in a CNN interview, Unsworth mocked Musk's offer of a mini-submersible from SpaceX for the rescue as a public relations stunt, and said the Tesla founder could "stick his submarine where it hurts."

The "pedo guy" tweet came two days later, and when a Twitter user asked whether he was really suggesting that Unsworth was a paedophile, Musk tweeted "Bet ya a signed dollar it's true."

On the witness stand on Wednesday, Musk downplayed that tweet, saying: "It's obviously a low-stakes wager."

He also said his tweets were "off the cuff," having testified on Tuesday that they came after he had just watched a video of the CNN interview.

Musk said that while he was used to facing criticism of his work, Unsworth's comments had been "extremely rude and contemptuous" and "denigrated the efforts of my team."

US District Judge Stephen Wilson has said the case hinges on whether a reasonable person would take Musk's tweets to mean that he was calling Unsworth a paedophile.

To win the defamation case, Unsworth needs to show that Musk was negligent in publishing a falsehood that clearly identified him and caused him harm.

"Actual malice" by Musk does not need to be proven because the judge deemed Unsworth a private individual, not a public figure.

Although the case does not involve Tesla, Musk's Twitter habits have long been under close scrutiny, with the company's investors and regulators expressing concerns about his tweets.

With 29.9 million followers, Musk's social media account is a major source of publicity for Palo Alto, California-based Tesla, which does not advertise.

Other witnesses for Unsworth are expected to take the stand after Musk finishes his testimony.

The hearing is expected to last about five days.