A passenger travelling on Qatar Airways' Doha-Cape Town flight is suing the airline after a spider-bite on-board turned fatal, nearly costing him a leg, or worse, his life, said a report.

Jonathon Hogg recounted the horrific moments that followed the venomous bite to the Press Association (PA), saying his leg had ballooned minutes after he felt a sharp pain in his left leg.

Within hours the 40-year-old's leg had turned black, and by the time he reached hospital it was "bursting open".

"The pain was like nothing I've been through in my life. By the time I got to hospital my leg was bursting open, there was pus, it was black.”

“It was a right mess. They told me if I had been any later I would have lost my leg or even died. It was terrifying," Hogg told the PA.

Doctors were forced to cut away a large portion of the flesh that was eaten by the venom and what was left "resembled something from a horror film".

He spent a month in hospital in South Africa, undergoing three operations and a skin graft, but three months on is still receiving medical treatment, the report said.

Hogg’s ordeal started when he had boarded a flight to South Africa. Six hours into his journey he felt a pain in his leg before spotting a spider running across the floor.

“I turned on the light and clearly saw a spider running across the floor before hearing two stewardesses screaming 'Spider', but I wasn't sure if I had been bitten as it really wasn't very painful," the report cited him as saying.

After his leg started to swell and bruise, he sought medical attention. Doctors diagnosed the bite from a brown recluse spider, which is venomous and potentially fatal, and warned him he could have lost his leg or even died if he had not been treated.

Hogg has now launched legal action against the airline.