Heffernan shows bomb to show security risk

Liberal senator Bill Heffernan held up what appeared to be a pipe bomb and some dynamite during a committee hearing to illustrate the "joke" that is parliament house security.

"Clearly you can do what you bloody well like," he told the Senate estimates committee hearing in Canberra on Monday.

The colourful veteran senator said up to now most people working in federal parliament knew it to be safe.

But he's concerned about new security arrangements being trialled and which have been criticised for being lax.

"I don't think it any longer is (safe) and to demonstrate that, this morning I brought in what could be, I brought this through security - a pipe bomb," he said.

Reaching into a plastic shopping bag, he produced what appeared to be several sticks of dynamite taped together.

The NSW senator said when he was a kid on the farm he used explosives to blow tree stumps out of the ground.

"We could blow a tree the size of this building out of the ground," he said.

Senator Heffernan said there was nothing to stop someone bringing explosive ingredients into the building through security.

Australian Federal Police commissioner Tony Negus agreed this could happen.

"Under the current arrangements, that is a risk," he said.

Mr Negus later said Senator Heffernan had showed him his supposed bombs before the hearing and he was satisfied they were inert.

He said that was why there was no reaction from his officers in the hearing room "who in different circumstances might have responded quite differently."

"I wouldn't encourage others to try and make that point because it might not be so responded to," he said.