It is understood the construction union will allege several contractors, working on the ACT Government's billion-dollar project, underpaid workers.

It is the second wage theft lawsuit filed by the union this year, with allegations up to $70,000 had been kept from employees on a $300-million ACT government office project.

CFMEU ACT secretary Jason O'Mara accused the government of abandoning workers and walking away from an election commitment to legislate a secure local jobs code intended to stop exploitation.

The government has promised a raft of legislative, regulatory and administrative changes to ensure the government awarded contracts to companies that met the highest ethical standards.

It released a discussion paper on the package in February, and has been reviewing feedback and conducting consultations since.

ACT Workplace Safety and Industrial Relations Minister Rachel Stephen-Smith said the government remained committed to the changes.

But the process has taken too long for the union, which this week heaped pressure on the government via a leafleting campaign, which alleged Ms Stephen-Smith had abandoned the pledge.

And Mr O'Mara warned the campaign could escalate to include phone calls and door knocking if the issue remained unresolved.

"We're almost two years on from the election and all we’ve seen from Minister Rachel Stephen-Smith is a draft code that will provide no real protection to construction workers," Mr O'Mara said.

"While Minister Stephen-Smith has sat on her hands, wage theft continues on ACT Government projects.

"We’ve previously identified up to $70,000 worth of wage theft at the Constitution Place site right next to the Assembly. In addition, this week we'll be lodging documents in the Federal Court that reveal wage theft on the Government’s Light Rail project totalling $700,000."

Mr O'Mara said his members had been outraged that their tax dollars had gone to employers who tried to rip them off, and many other companies felt they’d been disadvantaged in the tender process.

"The time for talk is over, now it's time for action. We'll be campaigning on this issue over the coming months until it is fixed," he said.

"It's too important to our members to walk away from. We've already sent out a flyer to everyone in Kurrajong letting them know about Minister Stephen-Smith's inaction on this issue.

"We won’t stop there. We'll keep sending out flyers, we'll do phone banks and we will run door knocking sessions until this issue is resolved."

Ms Stephen-Smith said the government had completed "significant and detailed work" to develop a Secure Local Jobs Package "that will ensure our procurement processes promote the highest ethical and labour standards in ACT Government contracts".

The minister said the work had been complex and detailed to ensure the new laws would "provide stronger protections for workers in organisations that perform work for the territory government than have been achieved in any other state or territory to date".

"We have been working through extensive feedback from unions as well as representatives of the business community in order to achieve the best outcome for workers in the ACT," she said.

"The Government remains committed to implementing a package of measures that will ensure that the ACT Government contracts only with companies that respect workers’ rights and treat them fairly."