Fart lights patient

A patient's "gas leak" is being blamed for bringing a hospital operation to a fiery end.

The man suffered minor burns in a brief but "dramatic" operating theatre fire which is believed to have been caused by flatulence, The New Zealand Herald reported today.

The man was at the Southern Cross Hospital in Invercargill to have haemorrhoids removed and was singed in the "exceedingly rare" incident involving his own gas.

"This was thought to be flatus containing methane igniting," a health source told the newspaper.

"There was a sort of flashfire and that was it, but it was fairly alarming at the time."

Haemorrhoids are swollen veins in the lining of the anus. If they protrude outside the body and become troublesome, they can be removed by surgery, which in the Invercargill case employed an electrical "diathermy" machine. A hand-held tool for cutting tissue and cauterising to stop bleeding, it produces heat and can spark.

Southern Cross is releasing little detail other than confirming an "electrical fire" occurred on March 22 and that it commissioned an independent forensic scientist to investigate.