A 33-year old Frenchman has survived 95 per cent burns after his "hero" twin brother gave him half of his own skin in the most extensive such graft ever, according to doctors.

Franck Dufourmantelle suffered severe burns after chemicals he was handling as an operator of dangerous materials in a factory caught fire and, in his words, turned him into a "human torch from head to toe".

Given the extent of his horrific injuries, when he reached hospital, doctors said his chances of survival were as low as one per cent.

However, the odds improved considerably when they were informed that he had an identical twin brother.

"His chances of survival were minimal. A severe burn patient dies when his own skin becomes a poison. But when I learned that Franck had an identical twin [from the same egg], the skies lifted," said Professor Maurice Mimoun, a plastic and reparatory surgeon. "Their genetic make-up is identical. It's as if it were his own skin."