It is believed the attackers climbed over the fence at the zoo

Staff at Dudley Zoo spotted three children aged between eight and 11 acting suspiciously shortly before the attack last Wednesday.

The five-month old marsupial was later found in a pond.

A zoo spokesman said the incident - which was captured by CCTV cameras - had "sickened" staff. The three boys have been released pending inquiries.

Staff shocked

Zoo chief executive Peter Suddock said: "The other six members of the wallaby family were obviously distressed, but they are okay now."

Mr Suddock added he was considering installing extra CCTV cameras.

Graham Chilton, head keeper at Dudley Zoo, said he was shocked by the incident.

"My initial reaction was one of shock and horror, how can someone do this to such a defenceless animal.

"The staff are shocked by the whole incident.

"Its mother was very stressed, but I've spoke to the keepers concerned and the group seems to have calmed down and are back to normal now."

It is believed the attackers climbed over the fence to get to the animal.