London (CNN) A tourist is suing British Airways, claiming he suffered injury and loss of earnings from having to sit next to an obese passenger on a 12-hour flight.

Stephen Prosser, 51, from Penygraig, South Wales, told Pontypridd County Court on Friday that British Airways cabin crew ignored his warnings he would be injured if he was forced to sit next to the man, the Press Association reported.

Prosser, a freelance civil engineer, described the individual as being "extremely large," 6 feet 4 and more than 300 pounds.

Prosser likened his fellow passenger's build to that of late rugby star Jonah Lomu, pictured right.

"He was that large that he had to force his buttocks between the arm rests of the seats," Prosser said.

The man sat "with his knees wedged against the seat in front and the rest of his body was over spilling into my seat by some inches" on the flight from Bangkok to London in January 2016, Prosser said.

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