Elon Musk has become involved in a spat with the British rescue diver responsible for saving 12 Thai boys from a flooded cave - labeling him a 'pedo guy' in an astonishing and unsubstantiated personal attack.

The boys and their football coach were saved from the Tham Luang cave by an international team following a week of tense rescue missions.

In the face of backlash over his baseless comment, the billionaire doubled down, claiming the expat diver's decision to live in Thailand was suspect ('sus').

Writing via his Twitter page, he attempted to cast doubt on whether the Brit was even involved in the rescue.

'Never saw him at the cave,' he wrote after the experienced caver rubbished Musk's own plans to save the boys.

The Tesla boss and tech entrepreneur had previously offered to assist the rescue mission by building a miniature submarine.

But this idea was dismissed by 63-year-old Vernon Unsworth who accused Musk creating a 'PR stunt'.

Unsworth, who led parts of the operation, said Musk 'can stick his submarine where it hurts'.

Later, when challenged by a social media user, Musk refused to withdraw his groundless attack.

'Bet ya a signed dollar it's true,' he wrote. 

'It just had absolutely no chance of working. He had no conception of what the cave passage was like' Mr Unsworth earlier told CNN.

'The submarine, I believe, was about five-foot-six long, rigid, so it wouldn't have gone round corners or round any obstacles.'  

In a series of tweets responding to a journalist Musk said: 'Never saw this British expat guy who lives in Thailand at any point when we were in the caves. Only people in sight were the Thai navy/army guys, who were great. Thai navy seals escorted us in — total opposite of wanting us to leave.

'Water level was actually very low & still (not flowing) — you could literally have swum to Cave 5 with no gear, which is obv how the kids got in. If not true, then I challenge this dude to show final rescue video. Huge credit to pump & generator team. Unsung heroes here.

'You know what, don't bother showing the video. We will make one of the mini-sub/pod going all the way to Cave 5 no problemo.' 

Mr Unsworth knows the Tham Luang cave system where the boys were trapped very well, as he has spent years exploring it.

Musk was mocked online after the boys were rescued without the aid of his submarine - but he has hit back at critics and said the dive teams encouraged him to continue the work. 

Read more on dailymail.co.uk.