Lulu, a 24-year-old white rhinoceros housed at Budapest Zoo, is now five months pregnant. The gestation period for a rhinoceros is 18 months, twice that of a human.

"We are confident that her baby will be born in good health in 2005," said Robert Hermes, a zoologist at the institute.

The northern white rhino lives only in the Democratic Republic of Congo's Garamba National Park, according to the World Wildlife Fund.

WWF said there are currently only 30 rhinos like Lulu left in the world, with 10 of them in zoos where they have been unable to reproduce.

The Leibniz Institute added that it was preparing for a second insemination of a white rhinoceros in a zoo in Dvur Kralove in the Czech Republic.

The white rhinoceros' main threat is man, who for years have slaughtered the animal, primarily for the horns which are considered by some as an aphrodisiac.

Next to the elephant, the white rhinos is the world's largest land mammal. An adult can measure up to two metres high and weigh as much as 3.5 tons.