A koala that was saved from a NSW bushfire by a woman using the shirt off her own back has been put down in a koala hospital due to his extensive burns.

Video footage Toni Doherty saving the koala from the Long Flat bushfire near Port Macquarie went viral a week ago.

The injured marsupial was taken to the Koala Hospital in Port Macquarie where his burns were treated and he was named Ellenborough Lewis after Ms Doherty's grandchild.

But the hospital on Tuesday delivered some bad news for all of those following the koala's progress.