Elon Musk doubled down on his description of a diver who helped rescue a group of trapped Thai boys from a cave as a 'pedophile', saying in an explosive court filing that he had been told the man was 'w****mongering' young girls in Thailand.

The Tesla chief also attempted to downplay the use of the word 'pedo' and said it means 'creepy old guy' in South Africa, where he's from, and not necessarily someone with a sexual interest in children.

The new remarks are part of a motion Musk filed in California court on Monday. DailyMail.com obtained the motion which in part describes why Musk believes his claims against Vernon Unsworth are not defamatory.

Unsworth caught the millionaire's attention after accusing him of grandstanding by offering to use Tesla's technology and engineers to rescue the boys. He said Musk's plan was unrealistic and would not work.

In retaliation, Musk tweeted: 'Sorry pedo guy, you asked for it'.

He then emailed BuzzFeed, claiming to have spoken to a private investigator who he said told him Unsworth was a pedophile who had moved to Thailand to marry a young bride.

Elon Musk doubled down on his rebuke of Vernon Unsworth on Monday in an explosive court filing, saying he hired a private investigator to look into the British native after apologizing to him publicly for calling him a 'pedo guy'. Unsworth is shown, right, receiving an MBE in June

Musk then challenged Unsworth to sue him. The British native filed a defamation lawsuit last year.

In his court filing, Musk asks the judge for a summary judgement and explains all the reasons why he thinks he is innocent of defamation.

He also tells how he hired private investigator James Howard after calling Unsworth 'pedo guy' on Twitter and says he paid him $50,000 to look into the Brit.

The first reason Musk gives is an apparent explanation of why he is not guilty of defamation is described as follows; 'Musk based his comments to BuzzFeed on what a private investigator said about Mr. Unsworth, both in written reports and by phone, based on an investigation he claimed to have undertaken in Thailand and England.

'The investigator reported that Mr. Unsworth was a fixture in Pattaya Beach, Thailand, a locale notorious for prostitution and child trafficking, that he had a taste for young Thai girls, that he w**re-mongered his way through the go-go bars of Thailand, that his only friends were his 'sexpat' peers, and that he married his Thai wife when she was a teenager, after starting a relationship when she was a young girl.'

The Thai soccer team got lost in caves while exploring and became stuck for days. Musk offered to help and sent a team of Tesla engineers to build a submarine to get them out

Musk tweeted this last July after Unsworth told CNN the Tesla CEO's plan to rescue the boys with a submarine would not work

It then says he sent the claims to BuzzFeed, 'making clear it could not publish any of his statements because they were 'off the record' '.

'He believed they would further investigate rather than simply publish his well-founded concerns,' Musk's lawyer writes.

He says he had no way of knowing BuzzFeed would print his claims without further proof of them and that it's not his fault the media outlet did.

The motion goes on to say that while the private investigator's information was dud - it 'does not matter'.

'Musk had a constitutionally-sufficient basis to say what he said to BuzzFeed.

'Although it turns out that the investigator lacked solid evidence of Mr. Unsworth's behavior, that does not matter here,' it says.

Another reason he thinks he is innocent of defamation, he said, is that in South Africa, where he is from, 'pedo' is slang for 'creepy old guy' and say it was cruel of Unsworth to attack his 'herculean efforts' to save the boys.

The motion goes on to accuse Unsworth of 'inserting himself' into the rescue mission.

He also criticizes him for speaking in the media about the plan to save the soccer team of boys.

Unsworth was one of the divers at the scene. He is shown with his wife, who Musk claimed he'd married when she was 12

Musk claims that unlike Unsworth, he was 'asked to help'. The plea came from a Twitter user.

''Pedo guy' was a common insult used in South Africa when I was growing up. It is synonymous with 'creepy old man' and is used to insult a person's appearance and demeanor.

'I did not intend to accuse Mr. Unsworth of engaging in acts of pedophilia.

Unsworth's wife Woranan Ratrawiphukkun, 40, previously dismissed the row in an interview with DailyMail.com

'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,' he said.

It also says that he was 'stunned' when he saw Unsworth's interview on CNN.

It occurred after all of the boys had been rescued and after Musk had donated the submarine he built for them - which never ended up being used - to the Thai Navy, he said.

He said: '[Mr. Musk] can stick his submarine where it hurts. It just had absolutely no chance of working. He had no conception of what the cave passage was like.

'The submarine, I believe, was about 5 foot 6 long, rigid, so it wouldn't have gone round corners or round any obstacles. It wouldn't have made the first fifty meters into the cave from the dive start point. Just a PR stunt.'

Musk took great offense.

'Mr. Musk had dropped what he was doing, diverted the work of dozens of his top engineers, donated all of their time and materials, overseen the design, manufacture, and testing of submarines, flown them to the cave system, and delivered them to the Thai government.

'Mr. Musk chose to correct the record and fight back,' the motion reads.

He then tweeted four times about it and, days later, was forced to issue an apology at the request of the Tesla board.

Musk however then retained James Howard, a private investigator, who told him he had 'skeletons in his cupboard'. He paid $50,000 on Howard's services.

Within 'days', Howard contacted Musk to say: 'there is indeed an unpleasant undertone to some of his lifestyle choices and [t]here is no question that [he] 'associates' locally with Europeans who enjoy 'Thai comforts' that are not acceptable in a developed society.'

Howard then told him he had reason to believe Unsworth met his wife , 40-year-old Woranan Ratrawiphukkun, 40, when she was 12.

Ratrawiphukkun previously spoke to DailyMail.com exclusively to laugh off the Tesla mogul's outlandish accusations.

Howard's investigation in Thailand continued.

He provided Musk's teams with updates including one which read: '[S]ome of the UK and Dutch divers who also volunteered stated that Mr. Unsworth was not a popular or particularly liked man in the Cave Rescue Team.

'When pushed as to why, they simply replied 'Creepy.''

In August, he exchanged emails with Ryan Mac, a BuzzFeed reporter. Musk claims that he stated in his emails where he made the allegations against Unsworth that they were 'off the record'.

Mac then emailed him, he said, telling him he intended to publish them because he never agreed to his terms.

Musk replied: 'If you want to publish off the record comments and destroy your journalistic credibility, that's up to you.

'As for answering more questions, I would be happy to do so, but not with someone who just told me that they will not honor accepted rules of journalism.'

Unsworth was given an MBE by Queen Elizabeth in June.

He moved to Thailand from St Albans in England years ago and took up cave diving as a hobby. He stepped in to help when the boys became trapped in June 2018.