Victorian-based blast-proof specialist Steelvision threatened the Reserve with bad publicity over claims of unpaid invoices for ballistics, hydraulics and steel for the $55 million state-of-the art cube that can guard up to $73 billion in cash.

The company is now at the centre of a Victoria Police investigation after it left more than 400 businesses $21 million out of pocket and a blast-proof fitout at Parliament House 15 months overdue.

The latest revelations follow allegations the company's owner had "a thousand dollar a day" cocaine habit, a sideline in an Uber-style app for escorts and mounting debts to Russian friends.

New emails obtained by The Sydney Morning Herald and The Age show Steelvision owner David Gooley threatened the Reserve in correspondence between himself, RBA project manager Simon Page and head contractor Watpac.

"As a business we were praised for our work at the opening by the governor of RBA so it makes it very hard to understand why we should have to carry an $800,000 debt at the end of the project," he said.

"I am sure RBA would not want any negative press relating to one of their stand-out contractors not being paid!"

Described as Australia's Fort Knox, the RBA's National Banknote Site supervault in the suburb of Craigieburn in Melbourne's outer north is manned continuously by armed guards and uses fingerprint scanners, reinforced trucks and robots.

"It is extremely secure, I have never come across anything like that in my life," said a source who worked on the project. "It is a one-off."

The supervault can hold all 1.5 billion banknotes in circulation, worth $73 billion or 4.3 per cent of the Australian economy.

It is understood representatives of other reserve banks around the world have visited the site to guide the design of their own vaults.

Despite the acclaim for the project, Mr Gooley accused the contractor and the RBA of "crippling our business".

In a series of emails in April 2017, after his company had worked on the project for about a year, he listed more than $800,000 in extra costs that were not taken into account during the initial contract. The total value of the security work was $3.5 million.

"We undertook this project to make a statement in the secure and ballistic market and upheld our side of the bargain by providing a service beyond expectation," he said.

"If the intent is to steer Steelvision towards administration and financial ruin then it is working.

"We are constantly trying to pacify our supply chain assuring them based on false promises from Watpac and RBA. This is nothing short of an absolute disgrace.''

On Friday, Mr Gooley said his experience with "Watpac and the RBA was amicable throughout" and that his personal life choices had nothing to do with the project.

Police checks were undertaken before contractors were allowed on site and all work was inspected by independent engineers. The payments have since been resolved between the parties.

The RBA dispute came months before Steelvision began the $14 million subcontract to build blast-proof doors at Parliament House.

That project has since blown out by 15 months and $1.5 million. Three of Parliament's top executives have taken redundancy or are on "personal leave" amid the fallout.

According to auditors Hamilton Murphy, the company could have been trading while insolvent during both the RBA and Parliament projects.

The auditors, who asked for the company to be put into liquidation in March, said Steelvision struggled under cash-flow challenges and a lack of payments from clients.

Steve Mowett, the former business partner of Mr Gooley, alleged in March that Mr Gooley used "prostitutes and a massive amount of drugs" and this was also to blame.

Mr Gooley, 41,spent a $400,000 grant from the Victorian government intended to hire new workers to pay off company debt from April 2018, the auditors said.

He took out a $70,000 cash loan from Russian loan sharks at a 72 per cent interest rate and floated investments in "Boober", an Uber-style service for escorts, when projects fell behind and debts continued to mount.

Emails from its real estate agent show that by September 2018, Steelvision could not afford to pay its rent in Canberra. Many workers went without pay over Christmas and the company now owes 400 creditors $21 million.

Mr Gooley said he was "no saint" and admitted he had been on a UEFA champions league "bender" in Ukraine at the height of the company's troubles.

The Victorian government referred the company to police over suspected fraudulent conduct in May.

The Reserve Bank and Watpac declined to comment.