Senator Bill Heffernan, a member of the ruling conservative Liberal Party, held up the pipe and what appeared to be some sticks of dynamite during a committee hearing in Canberra.
"Clearly you can do what you bloody well like," said Heffernan, an outspoken former farmer who became a member of the national parliament in 1996.
Heffernan said until now most people working in parliament felt safe, but that new rules being trialled put this at risk by allowing some people with passes, including politicians, and their belongings to no longer be scanned on entry.
Heffernan said when he was a child, people used a combination of ammonium nitrate, distillate and gelignite and a detonator to fell trees.
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"You would blow a tree the size of this building out of the ground," he said.
"At the present time there is nothing to stop anyone from bringing in those ingredients in here over a period of time through security."
"Under the current arrangements, that is a risk," he said.
Negus later revealed that Heffernan had shown him the objects before the hearing and he was satisfied they were inert, adding that this was why security officers had not responded when they were produced.
The security changes introduced this month mean that those with photographic ID cards issued by the government are not screened with metal detectors or X-rays at private entry points, reports said.
Department of Parliamentary Services secretary Carol Mills told the Canberra Times that parliament still had higher security screening than state parliaments and most government offices in the nation's capital.