Teenage conservationist Bindi Irwin, daughter of late "Crocodile Hunter" Steve Irwin, has revealed her shock that an essay she penned for Hillary Clinton was edited so heavily that her words were "twisted".

Iriwn, 14, was reportedly invited to write for US Secretary of State Clinton's e-journal about why she had chosen to work in wildlife conservation and wrote 1,000 words that largely focused on the issue of overpopulation.

But she told Sydney's Daily Telegraph that when the piece had been edited and returned to her for approval, it had been altered so much she felt she had to withdraw it from publication.

"When I got the essay back after they edited it, it was completely different," the newspaper cited her as saying.

"I hadn't said anything they had put in... my words were twisted and altered and changed. I was a little bit shocked to tell you the truth."

Irwin's essay described Earth's expanding population and the planet's struggle to support it, using the simple analogy of a child's birthday party in which 15 people were invited and catered for and 70 turned up.

During the edit, however, the overpopulation issue was airbrushed.

"I was really sad and I think it was more frustration because I'm trying so hard to get the message across and I guess some people don't want to listen," she said.

Her mother Terri Irwin, who has been raising her daughter and nine-year-old son Robert alone since her husband died during a freak accident in 2006, said the edited version was withdrawn from publication at Bindi's request.

"It's interesting that she was asked to write an essay about the environment and included the consideration of population (growth) and they returned her essay edited and completely edited that out," Terri Irwin said.

"So Bindi wrote to Hillary Clinton's organisation and said 'What happened to freedom of speech? This is my opinion and I don't want that edited out'."

Bindi Irwin said the incident had not damaged her admiration for Clinton.

"I would love to see her running for president one day because she's doing a really great job," she said.

Environmentalist Steve Irwin, known for his daring stunts with dangerous animals, died after being stung by a stingray barb to the chest while filming on Australia's Great Barrier Reef.

Since his death, Bindi Irwin has become a media star in her own right, promoting her father's conservation causes and starring in her own television programmes.