CANBERRA (Reuters) - The parents of a 7-year-old boy who broke into an Australian outback zoo and fed a string of small animals to its resident crocodile are likely to be sued after police said the boy was too young to be held responsible.

A turtle, four western blue tongue lizards, two bearded dragons, two thorny devil lizards and a 1.8 metre (5.9ft) adult female Spencer's goanna were fed or led into the jaws of a 3 metre, 200kg (440lb) saltwater crocodile named "Terry."

Security camera footage at the Alice Springs Reptile Centre showed the smiling youngster also bludgeoning to death a small blue tongue lizard and two more thorny devils during a half-hour of breakfast-time havoc last Wednesday.

"The fact a 7-year-old can wreak so much havoc in such a short time, it's unbelievable. In my day he'd get a big boot up the backside," centre director Rex Neindorf told Reuters by phone.

"Police found him, but in the Northern Territory here he can't be accountable if he's under 10 years of age."

Neindorf said many of the animals fed to the croc were rare or mature and would be difficult to replace.

The boy was unknown at the centre and had "clammed up" when questioned by police on what sparked the rampage, he said.

Neindorf said he was now looking at suing the parents of the pint-sized terror, who could easily have been taken by Terry himself as he fed the croc from a small landing at his enclosure.

"We'll be looking at suing the parents, who were supposedly in control of him at the time," he said.