[ZenGum]

Sam the koala, made famous by footage of her drinking from a firefighter's water bottle during Victoria's bushfires, has died.

The badly burned koala became a symbol of hope for the survivors of the deadly bushfires that killed 173 people and left 7,500 homeless.

But just months after her rescue from the fires, Sam was diagnosed with cysts linked to the life-threatening disease chlamydia that has ravaged the koala population.

The four-year-old koala was due to have surgery on Thursday to remove the cysts but John Butler of the Morwell Vet Clinic discovered Sam had severe changes in her urinary and reproductive tract that were non-operable.

"Unfortunately Sam has been put to sleep. It's very, very sad," said Peita Elkhorne of TressCox Lawyers on behalf of the Southern Ash Wildlife Shelter.

"It was so severe that there was no possible way to be able to manage her pain."

Prime Minister Kevin Rudd said he was sad to hear of Sam's death.

"When I travelled to London for the G20 summit in early April, the symbol of hope for so many people around the world was the great picture of that wonderful koala being fed water by one of our firefighters," he said.

"I think that gave people of the world a great sense that this country Australia could come through those fires.

"Sam the koala was part of the symbolism of that and it's tragic Sam the koala is no longer with us."

This makes me sad; but at least she was given a quick humane end rather than the slow unpleasant one she would have met in the wild.