Elon Musk is attacking a diver who helped rescue a group of teenage boys from a Thai cave last week after the rescuer criticized Musk's mini submarine, which he designed to help with the mission.

Cave rescuer on Musk: “It was a PR stunt. It had no chance of working.”

British diver Vern Unsworth called Elon Musk's submarine rescue plan a "PR stunt." He did not hold back, saying that Musk can "stick his submarine where it hurts."

In an interview with CNN, Unsworth described Musk's mini submarine as useless and as nothing more than a grab for attention.

He also said the billionaire was asked to leave the cave.

"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," Unsworth said.

"It wouldn't have made the first 50 meters into the cave from the dive start point. It was just a PR stunt."

Unsworth played an important role in the dangerous mission and helped to connect British experts and Thai authorities.

He was a key member of the team because of his thorough knowledge of the cave system, which he spent six years navigating, CNN reported. He also has been involved in smaller cave rescue missions in the UK, and he advised local authorities to bring on a team of expert divers.

"It was a race against time," he told CNN. "They needed world-class divers and that's what we got."

The boys were found only 200 meters away from the location where Unsworth predicted they’d be; it was "probably around about the best place they could have been," he told the news outlet.