“The mother pushed them away. We had no choice,” the zoo's Bo Kjellsson told the Borås Tidning (BT) newspaper.
Lioness Karafi gave birth to the three cubs last Friday, delighting zoo staff and visitors. But the mother then failed to show any interest in the new born lions.
Karafi refused to nurse the new cubs, leaving them to themselves while she chose to spend time with the rest of the pride.
The newborns became weaker and weaker, and on Saturday zoo officials decided to put them down.
The option of bottle feeding the cubs was ruled out because doing so would have affected their behaviour for the rest of their lives, making it hard for them to live with the other lions.
“The cubs were fading away because the mother wasn't interested in them, therefore we helped them over the threshold,” said Borås Zoo's Carin Mortensen to TT.
“It always hits you hard when you're forced to put down newborn cubs, but we need to be professional. This happens in the wild and isn't out of the ordinary.”