A New Zealand lorry driver said he blew up like a balloon when he fell on to the fitting of a compressed air hose that forced air into his body at 100lbs per square inch.

Steven McCormack, 48, was standing on his lorry's footplate on Saturday when he slipped and fell, breaking a compressed air hose off an air reservoir that powered the brakes.

He fell hard on to the brass fitting, which pierced his left buttock and started pumping air into his body.

"I felt the air rush into my body and I felt like it was going to explode from my foot," he said from his hospital bed in the town of Whakatane, on North Island's east coast.

"I was blowing up like a football. I had no choice but just to lay there, blowing up like a balloon."

Mr McCormack's workmates heard his screams and ran to him, quickly releasing a safety valve to stop the air flow, said Robbie Petersen, co-owner of the haulage company.

He was rushed to hospital with severe swelling and fluid in one lung. Doctors said the air had separated fat from muscle in Mr McCormack's body, but had not entered his bloodstream.

McCormack said his skin felt "like a pork roast" - crackling on the outside but soft underneath.