Tesla founder Elon Musk apologised to British caver Vern Unsworth for comments he made about him following the rescue of a dozen Thai schoolboys and their football coach from a cave in northern Thailand.

Musk's engineers had developed a mini-submarine he believed could be used in the rescue attempt. Unsworth ridiculed the idea in an interview he gave after the boys were rescued by an international team, dismissing it as a 'PR stunt' and saying it would have had 'no chance of working'.

Musk, referring to Unsworth without naming him as a 'British expat guy who lives in Thailand', tweeted describing him as a 'pedo' [paedophile].

After a backlash against his comment, Musk deleted the tweet. He said in his latest tweet: 'His actions against me do not justify my actions against him, and for that I apologize to Mr Unsworth and to the companies I represent as leader,' Musk said in a tweet. 'The fault is mine and mine alone.'

Unsworth, who played a leading role in the rescue, said on Tuesday that he has been approached by British and American lawyers and will seek legal advice after Musk directed abuse at him on Twitter.

Musk also attacked the Thai official in charge of the rescue operation, Narongsak Osotthanakorn, for saying the submarine was 'not practical'.

Additional reporting by Reuters.