Scientists have succeeded for the first time in impregnating an elephant with frozen sperm, ultrasound pictures presented by Vienna's Schoenbrunn Zoo showed on Tuesday.

The scan shows a 10.6-centimeter-long, 5-month-old elephant fetus with its trunk, legs, tail, eyes and ears clearly discernible.

The fetus, which was scanned in April, is likely now twice that size, the zoo said, and is due to be born to 26-year-old African elephant Tonga in or around August 2013 after a pregnancy of about 630 days.

Elephants have been impregnated with fresh or refrigerated sperm in the past in an effort to protect endangered species, but frozen sperm can be transported farther, and this allows for the female elephant to be inseminated at her most fertile time.

The sperm was taken from a sedated wild elephant in South Africa using electroejaculation in the project known internally as "Operation Frozen Dumbo," a zoo spokeswoman said.

It took eight months to clear customs on its way to France due to lack of an established procedure for such wares.

The project was a joint effort of Schoenbrunn Zoo, Berlin's Leibniz Institute for Zoo and Wildlife Research, France's Beauval Zoo and Pittsburgh Zoo in the United States.

Both African and Asian species of elephant are endangered, especially the Asian, mainly due to poaching, and destruction of their habitats.

"Since the survival of elephants in their natural habitat is under threat, zoos around the world are striving to preserve them," said Schoenbrunn Zoo Director Dagmar Schratter.

"Artificial insemination with the semen of a wild bull elephant is a chance to enrich the gene pool to further species conservation," she said, adding that there were five female elephants living in zoos to every one male.