Zookeepers in the German city of Hanover have been accused of abusing young elephants after allegedly being filmed by local activists.
Broadcaster ARD said it had received footage reportedly showing zookeepers hitting young elephants with so-called "elephant hooks" – a 70cm rod with a metal hook and tip at the end.
The show reported that the zookeepers used the instruments to coerce young animals to do tricks.
In one instance caught on film, Report Mainz said that a zookeeper can be seen dragging a baby elephant up by the neck, causing the young animal to cry out.
The zoo, which is one of the oldest in Germany, has denied the report, saying that the elephant hooks are used as "tools of guidance" for the elephants.
"Our animal keepers work in a team with their animals. None of them would maliciously hurt an animal," said zoo director Andreas Casdorff, insisting that their relationships with the animals are ones of deep, mutual trust.
The footage was also given to American elephant expert Carol Buckley for her to study.
"One mistake by the elephants leads to immediate punishment, bodily pain, harassment, intimidation and emotional stress. The elephants at Hanover Zoo live under constant threat," said Buckley.
"The elephants in Hanover zoo suffer from learned helplessness and live in daily fear."
The animals at Hanover are trained by the so-called 'direct-contact' method, which is "now outdated" according Professor Manfred Niekisch, director of Frankfurt Zoo.
"Beatings and chains are things from the past, when people thought they must dominate the animals," Niekisch said.
After being confronted with the footage, the zoo insisted that the recordings do not discernibly show the animals being beaten. Instead, zoo director Casdorff said the zookeepers were simply guiding the elephants
"They have to regularly do the exercises so that they can train the animals to respond to them in medical situations," said Casdorff.