Two rare southern white rhinos have become pregnant at the same time at a zoo in Belgium, boosting efforts to save the endangered species.

The news that both Elie and Madiba conceived after "natural" relations with the zoo's male rhino Jobi, came after a calf was born in San Diego zoo, the US, on Sunday.

Pairi Daiza zoo spokeswoman Claire Gilissen said the news was "fantastic" for all the team members who are doing their "bit for the protection of this species."

There are around 18,000 southern white rhinos in the wild but the subspecies is being exterminated by poachers at a rate of one every eight hours.

Another species of rhino, the northern white, is in even more critical danger, with only two left in existence.

The remaining northern white pair are both female, so they will die out unless their genes can be preserved or recovered and an artificial breeding program begins.

AFP