AAP

When “miracle” elephant Mr Shuffles was born against the odds two years ago at Taronga Zoo, keeper Lucy Melo played an integral role in raising him.

But, just before 11.30am (AEDT) on Friday in the elephant barn at the Sydney harbourside zoo, the Asian elephant calf “challenged” Ms Melo and pinned her against a bollard.

Ms Melo, the zoo’s 40-year-old senior elephant keeper, was crushed and is fighting for her life in Sydney’s Royal North Shore Hospital.

“I am very, very concerned about the staff member that has been hurt, as are all of the team at the zoo,” Taronga Zoo director and chief executive Cameron Kerr told reporters.

Ms Melo is in a critical but stable condition.

The elephant, who weighed more than 500kg at his first birthday, earned the nickname Mr Shuffles because his early attempts at walking resembled the shuffle of an elderly man.

On Friday Ms Melo was engaged in a routine training session to teach the elephants how to wash.

Two other keepers heard her cries and moved the elephant away.

Ms Melo was still conscious and talking when paramedics arrived but lapsed into unconsciousness and had a cardiac arrest for about five minutes.

A second crew of paramedics managed to get her heart beating again before rushing her to Royal North Shore Hospital in a critical condition.

The zoo said it didn’t know why the two-year-old elephant challenged Ms Melo, who was part of the team that went to Thailand to bring Taronga’s five Asian elephants to Sydney.

“Since the herd arrived in 2006, three calves have been born and Lucy has been part of raising the calves and looking after the extended family,” the zoo’s website says.

Both the zoo and Workcover NSW are investigating the incident.

Mr Kerr said the public were not at risk during the incident, which happened as part of a “normal animal washing routine”.

It is not the first time in Australia that an elephant has turned on its handler.

In 2007, Stardust Circus worker Ray Williams, 57, was found dead in the elephant Arna’s enclosure at Yamba, in northern NSW.

An interim post-mortem examination found Mr Williams suffered a broken back and a ruptured aorta and died from “severe blunt trauma”.

A year later after undergoing health and behavioural assessments, Arna found a permanent home at Taronga Western Plains Zoo.

According to Taronga’s website, Ms Melo has worked at the zoo since 2004, following stints in the United States at Houston Zoo, Rio Grande Zoo and Disney’s Animal Kingdom.

In a article on its website Ms Melo said: “Every day I work with animals is amazing, but the highlights are definitely the births of our elephant calves.

“I enjoy the one-on-one relationships that I have with the elephants … They truly give you unconditional love.”