Polar bear cub born at Berlin zoo dies

Tierpark Berlin zoo's polar bear cub Fritz has died after being struck down by a mystery illness. Photo / Zoo Tierpark Berlin

Berlin's Tierpark says a polar bear born at the zoo last November has died.

The zoo, in the eastern part of the German capital, says 4-month-old Fritz fell ill at the weekend.

Vets separated him from his mother, Tonja, on Monday to conduct tests, which indicated a liver inflammation.

Fritz, with his mother Tonja, had yet to make his public debut, but many photos of him appeared on the zoo's social media accounts. Photo / Tierpark Berlin

The zoo said vets were unable to find the precise cause of his illness and Fritz died late on Monday.

In a statement Tuesday, zoo director Andreas Knieriem said: "We are devastated. It's incredible how fond we had become of that little polar bear."

Like Berlin's famous polar bear Knut, who succumbed to illness aged four in 2011, Fritz had a twin who died shortly after birth.

The cub was born on November 3, 2016. Photo / Tierpark Berlin