The Copenhagen Zoo says the lion family was put down Monday to make way for a new male who posed a danger to the cubs.
"Because of the pride of lions' natural structure and behavior, the zoo has had to euthanize the two old lions and two young lions who were not old enough to fend for themselves," the zoo said in a statement.
The zoo claimed the new male would have killed the 10-month-old cubs "as soon as he got the chance."
The new lion will arrive within the next few days. The zoo says it made a failed attempt to find new homes for the lion family before bringing him in to start a new pride as part of its lion breeding program.
The Copenhagen Zoo is infamous for killing Marius, a young giraffe, with a bolt gun, and then dissecting his body and feeding him to lions while visitors watched. Marius wasn't allowed to reach adulthood because of European zoo rules on giraffe interbreeding, the zoo said.
"Marius hasn't made us the least bit afraid, because what we are doing is the most correct thing to do," zoo chief Steffen Stræde said.
The lion family's bodies won't be cut up in public, because "not all our animals are dissected in front of an audience," a zoo spokesman said.
[Photo: AP Images]