TWO rare Eastern black rhino calves have been born in a week at Chester Zoo, boosting global numbers of the critically endangered species.

Both calves were delivered safely onto soft sand following pregnancies lasting around 15 months.

Incredible CCTV footage shows the birth and adorable wobbly steps of the first calf, with the youngster getting to its feet only minutes later.

The first of the precious pair was born to mum Kitani, 20, on Monday June 19 with the second arriving exactly one week later (Monday, June 26) to 10-year-old Zuri.