CEPU communications division national president Shane Murphy said what he called Prime Minister Malcolm Turnbull's NBN was a "shambolic mess".

He said the Four Corners programme about the project had revealed a myriad problems, both for consumers and workers.

“The NBN was meant to be a critical piece of nation-building infrastructure, but at the moment it’s nothing more than a national embarrassment,” Murphy said.

“The NBN had the potential to be a world-class network and provide jobs and training opportunities for workers to develop new skills. Instead, we’ve ended up in a situation where we’ve got frustrated customers on a shonky network being held together with plastic bags and ringbarked cables.

“This is Turnbull’s NBN – a national joke."

Murphy said the Prime Minister could try to handball the blame but the reality was that the mess was all his making.

"We warned this government that this was coming, but the Prime Minister refused to listen. We’ve got thousands of subcontractors who are given no proper training and are being squeezed by principal contractors who are making billions at the taxpayer’s expense," Murphy claimed.

“This government’s flawed approach to this key infrastructure project is enabling that behaviour.

“Not only has the Prime Minister failed to deliver on his promises to deliver a better NBN faster and cheaper, he has failed the workforce by allowing the biggest pyramid sham contracting scheme the country has ever seen to flourish throughout the industry.”