The babies were born on November 21, and seemed to have been doing well, zoo authorities reported. But on Monday one died, followed by the death of its twin on Friday afternoon.
The babies had not been disturbed since their births, but were closely observed via cameras set up in the pen.
“Vera regularly suckled the juvenile, and it slept after each feeding, so that it could be assumed that it was being provided with sufficient milk,” said Dag Encke, zoo director.
The six-year-old female Vera had a baby about a year ago, but this was taken from her over fears she would not raise it safely, and it was reared by hand – Flocke became a top attraction for visitors in the wake of Knut-hysteria.
The twins, both said to be males, were left with the bear which was considered to be doing a good job looking after them until the first died last week.