Sharjah24 – Reuters: Northern Germany's Rostock zoo on Monday (November 22) announced the recent birth of polar bear twins and released a short video of proud mother "Sizzel" tending to her offspring.

German media quoting the zoo reported Sizzel was doing a "great job" looking after her two babies born on Nov. 14.

Cubs at birth weigh between 450 and 850 grams, a fraction of a grown female polar bear which during pregnancy put more than 500 kilos on the scale, according to Nuremberg zoo.

Polar bear cubs are born almost naked and it takes them up to two months to be able to stand up on their feet.

According to German media, Rostock zoo will ensure Sizzel and her babies are not exposed to any type of stress for now.

In 2011, Knut the celebrity polar bear at Berlin zoo died suddenly aged four, sending shock waves across his fan community all over the world.

Knut was rejected by his mother and hand-reared instead by his keeper Thomas Doerflein.

Thousands of visitors came to watch keeper and cub playing together, and Knut's fame spread around the world.