A zoo spokesman said both the mother, Tanya, and the baby bull, estimated to weigh somewhere between 85 and 105 kilos, were doing well.

But officials are cautiously warning that there is still a lot that can go wrong.

The baby, who arrived at 0100GMT on Friday, fed with assistance from keepers and within hours of his birth he was trying to feed from his mother.

Sister pregnant

"Tanya s is showing all the signs of being a very good mother," said the spokesman.

"We are keeping them indoors and isolated from the zoo's other four elephants."

The baby was fathered by Tembo, the sole adult bull at the zoo.

This time next year another baby should have arrived. Tanya's sister, Zola, is also pregnant.

Wait for visitors

The two have lived at the zoo since they were rescued from Zimbabwe.

Visitors will have to wait before they can see the new addition.

The elephant house remains closed while their progress is monitored round the clock.