The British caving expert who coordinated the rescue of 12 Thai children trapped underground has informed Elon Musk he is preparing to sue him, after the Tesla founder labelled him a “paedo” on Twitter.

Vernon Unsworth, 63, enraged the billionaire when he rejected his offer of sending a submarine to assist the rescue, pointing out that it was not a workable solution, and deriding it as a "PR stunt".

He said Mr Musk could "stick his submarine where it hurts."

Mr Musk hit back, calling Mr Unsworth a “paedo guy”, in a now-deleted tweet. He then issued an apology, and said he had tweeted “in anger”.