The keeper, whose heart stopped for 5 minutes in an incident witnessed by schoolchildren and other visitors, is in hospital fighting for her life.

"It's unknown at this time why the young elephant challenged the keeper," Taronga said in a statement. "The public were not at risk at any time and the elephants are now in their paddock at the zoo."

Pathi Harn, which in Thai means miracle, was born alive a day after staff, including an international expert on elephant births, declared he had perished in his mother's womb.

Berlin Zoo's Thomas Hildebrand, speaking in Sydney in March 2010, said the foetus had died because of its awkward position in the birth canal and that this was verified by the rest of the Taronga herd going into mourning.

"So they actually can hear the movement of the baby," he said the day before the miracle birth. "They lose interest if the calf is dead and the mother has to deal with this event by herself."

The injured woman is in her 40s and has been named in media reports as senior elephant keeper Lucy Melo.

Paramedics called to the zoo said the keeper was conscious when they arrived but had gone into cardiac arrest afterwards.

Lucy Melo has been at Taronga since 2004, following stints at zoos in the United States.Author: Sid Astbury