It is understood the apparent flaw means some sections of the buildings could be prone to collapse in a significantly faster time than what's expected in the national construction code.

Access Canberra's construction occupations registrar said the builders involved in the projects had been sanctioned, but denied there was evidence of a "systemic design flaw" in those complexes.

The government last week disputed claims from structural engineer Mal Wilson, reported in The Canberra Times, that it had been made aware of a design flaw uncovered in the Elara building - and possibly replicated in other buildings across the nation's capital - but had not done anything about it.

The government confirmed Mr Wilson had prepared a number of reports on the trouble-plagued Bruce complex, but said none had referenced widespread problems. It reaffirmed that position this week.

But The Canberra Times has seen a letter Mr Wilson sent to the government's construction services branch on March 23, 2013, which detailed his concerns about serious fire-safety and structural issues at Elara and at least five other buildings. Mr Wilson noticed the same design flaw at a Woden retirement village while he was inspecting solar panels on the building.

In the letter, Mr Wilson said he had observed a "very disturbing trend" while inspecting the complexes.

The Canberra Times has confirmed the buildings in question are: the Empire apartments in Forrest; a development in Fox Place, Lyneham; the Pulse apartments in Gungahlin; and Elara.

"It is our view that the design shortcomings are systemic and have been going on for many years and we fear that a significant percentage of Canberra apartments may be at significant risk especially in a fire situation," Mr Wilson's letter read.

Mr Wilson said in the letter that he had obtained a fire consultant's report on the Elara apartments, which concluded the building's columns and beams would not meet Australian standards, consequently creating a fire risk to residents and firefighters. The consultant was concerned the problem would not be fixed without "regulatory intervention".

The ACT's chief fire officer was sent a copy of the letter, as Mr Wilson believed firefighters needed to be aware of the building's condition before they responded to any incidents.

"I can only assume that hundreds of similar units and apartments have been constructed in Canberra in the last decade or so. I believe that these need to be identified and rectified as necessary in the interests of public safety."

The Canberra Times is not aware of any particular fire-related incidents at the Elara complex since it was completed in 2007.

However, the complex has been plagued by water leaks and other structural problems. In 2013, residents launched Supreme Court action against the builder, B and T Constructions Pty Ltd, seeking compensation for an estimated $20 million damage bill.

Those proceedings were suspended after B and T Constructions Pty Ltd was placed in liquidation, forcing owners to pursue compensation from the the builders' insurance scheme through the Federal Court.

A judgment in the case is expected in the coming weeks.

Following last Monday's report, Mr Wilson wrote to the head of Access Canberra, Dave Peffer, saying his agency's claim that it had not been warned about systemic design flaws at Elara was "simply nonsense" and "badly in need of correction".

In the latest letter, Mr Wilson said the Elara report presented to the government identified issues with 350 columns, 43 beams and 25 angles at the Thynne Street complex.

"The issue here is not that an engineering company made a mistake which can easily happen from time to time, but rather that they systematically went about design in a way that placed the occupants of the building at an unacceptable risk to their safety," the letter stated.

"If you make the same mistake 350 times it is by definition a systemic problem."

Mr Wilson said the government should, at the very least, commission an independent audit into the buildings he had red-flagged. He suggested there could be "at least 10 and perhaps even 100 times as many" Canberra apartments plagued by the design flaw.

He said the problem was "peculiar to the ACT" and none of his expert colleagues interstate had "seen anything like it".

Access Canberra construction occupations registrar Ben Green this week maintained that the government had not received a report from Mr Wilson in 2013 which provided evidence of a systemic design flaw at Elara and the five other buildings.

Mr Green said each development was a "bespoke" complex, where defects manifested as a result of different causes.

He said the regulator had taken action where possible, but could not confirm whether any of the defects, including those identified by Mr Wilson, had been partially or entirely fixed.

The regulator issued rectification orders against the builders of three of the apartments identified by Mr Wilson. The builder of two of those projects was hit with sanctions, which resulted in it being stripped of its licence and forced to commit to never to reapplying for one. In two cases, the company subjected to the action was wound up, meaning no action could be taken.

The government did not specify whether any of the sanctions imposed were related to the flaw identified by Mr Wilson.

In another case, the matter was resolved without any sanctions being imposed on the building company.