The zookeeper who punched a kangaroo in the face to save his beloved pet dog called police to his home after animal-rights supporters called him "ruthless" and a "pathetic excuse for a human being" online.

Greig Tonkins achieved internet fame when footage emerged of him punching the male kangaroo to defend his dog Max. The pair squared off during a boar-hunting trip organised for a young terminal cancer sufferer.

Mr Tonkins' employer, Taronga Western Plains Zoo, said there was "no suggestion" he would be fired over the punch, but added it was considering "appropriate action".

It described him as an "experienced" keeper who had "always followed Taronga's best practice approach to animal care and welfare".

But his actions attracted condemnation from activists.

Peta Australia said: "Punching a kangaroo in the face is neither brave nor funny. It’s illegal, as is harassing native wildlife with dogs."

Twitter users weighed in to call Mr Tonkins "the dregs of the dregs" and "clearly in the wrong".

An animal expert said Mr Tonkins was "very lucky" the kangaroo did not stick around for a fight.

Dr Mark Eldridge, of the Australian Museum, said: "Before kangaroos fight, they usually size each other up. If one doesn’t back down, they will get into an aggressive encounter.

"I think the kangaroo was still in the sizing up stage when he was hit with the punch, and so the man was lucky the roo decided to call it quits."