Tesla Inc 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.

"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.

Read: Tesla shares fall after CEO Musk calls British caver paedophile

The billionaire entrepreneur's spat with British caver Vernon Unsworth started last week, after rescue teams rejected Musk's offer of a mini-submarine created by his rocket company SpaceX to help rescue a 12-member soccer team and their coach trapped inside a flooded cave in the northern province of Chiang Rai.

"He can stick his submarine where it hurts," CNN quoted Unsworth as saying last week. "It just has absolutely no chance of working."

Musk shot back on Sunday on Twitter: "We will make one (video) of the mini-sub/pod going all the way to Cave 5 no problemo. Sorry pedo guy, you really did ask for it." The tweet was later deleted.

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