The L.E. Giles abattoir at Trafalgar was shut down when animal activists videoed a pig being slaughtered with a sledgehammer, ABC reports.

In his first interview since the closure, Colin Giles says he was pressured by industry regulator PrimeSafe to surrender his operating licence.

But he says the killing of pigs had been approved by the former Victorian Meat Authority, and the sledgehammer was used for safety reasons.

"They did use it on one pig that got away, but it's the quickest and most humane way to stop the pig," he said.

"There's fellas running around on the floor with knives and things in their hands, it's pretty dangerous and a pig's very hard to restrain.

"And the quickest way out is probably the most humane way out I think."

PrimeSafe denies any suggestion that it bullied the owners into cancelling the licence.