Knut passed away in his habitat this morning of still-to-be determined causes at the age of 4. A rep for PETA tells TMZ they contacted to Berlin Zoo months ago to alert them to the fact that Knut was being "terrorized" by three female polar bears -- including his own mother!
The rep tells us, "PETA Germany repeatedly asked zoo authorities to move Knut away from the three females to a different location. His premature death could possibly have been avoided. Polar bears don't belong in captivity."
A necropsy is planned for Monday to determine the cause of death.