A traveller with British Airways who was “wedged” next to an obese passenger during a 12-hour flight is reported to be suing the airline, claiming that he suffered back injuries as a result.

Stephen Prosser, 51, a company director from Tonypandy, south Wales, was repirted by The Times as saying that the 6ft 5in passenger was so large that he “spilled” into his seat by several inches.

Prosser, who is 5ft 2in and 10 stone, said he was “forced to adjust his body and sit in an awkward and uncomfortable position” for the duration of the flight from Bangkok to London in January 2016.

He said it resulted in soft tissue injuries in his back and he is seeking up to £10,000 in damages.

Prosser is claiming between £5,000 and £10,000 in general damages for pain, suffering and loss of amenity.

BA denies the claims, saying that Prosser “did not display any signs of injury” when leaving the flight. The airline claims that the passenger “did not have fat which was spilling over the arm rest”.

The case is due to be heard at Pontypridd county court.

A BA spokeswoman said: “As the case is subject to ongoing proceedings, it would be inappropriate for us to comment.”

The newspaper reported Prosser as saying: “Just as the plane door was about to close, this 6ft 5in elk, weighing about 23 stone got on board and sat between myself and another passenger who had the aisle seat.

“He was a huge bloke, not just overweight but really big boned as well. He was a real lump. I felt discomfort as soon as he sat down because I was pinned against the side of the cabin.”

During the flight Prosser asked cabin crew to move him to a different seat but they refused and instead offered him extra pillows and a blanket to support his back.

He said he had “no choice but to go back to my seat. The discomfort at being squashed up against the cabin soon turned to agony. I think it’s up to the staff to take control of a situation like that and they should have asked the passenger on the aisle seat to swap with the larger man in the middle.”

Defence documents say that Prosser asked to speak to the customer service manager immediately after take-off and refused to sit in his seat.

The airline manager was under the impression that he wanted an upgrade and told him that the flight was full.

Prosser told the manager that he would have back pain and would not be able to go to work if he was not moved. However, the manager found the comments “surprising”, the documents say, as it was less than half an hour after take-off.

The manager said that the passenger next to Prosser was “well built and over six feet tall, but certainly not fat”.