Heavily redacted ministerial briefs and meeting notes obtained under freedom of information indicate the government had doubts about the timeline the consortium building stage one light rail, Canberra Metro, had set out.

This was despite repeated public assurances the program would be completed on time.

As early as May, project director Megan Oldfield gave a presentation to the project board's meetings about the risks to the on-time delivery and how those were being managed.

A briefing note to Transport Minister Meegan Fitzharris from last August said while Canberra Metro maintained a December 21 completion date, there were growing risks to the project being completed on time.

"During the reporting period Canberra Metro have used most of the contingency allowances held within the program and are therefore at a higher risk of missing the forecast completion date," the minister was advised.

"Previous delays have been mitigated through the resequencing of logic and acceleration of activity durations, which has ultimately resulted in parallel execution of design and testing activities and a back-end compression of the program."

However, the brief said, "Canberra Metro’s current program again shows slippage against the program."

In early October, while noting Canberra Metro still held that the project would be ready by December 21, a brief to the minister said, "Transport Canberra does not yet have sufficient information to form a view as to the likely date of services commencement but is continuing to liaise with Canberra Metro in this respect".

Later that month, another brief from Transport Canberra officials said while Canberra Metro maintained the project would be completed by that date, the minister should change her language around the operational timeline to be more vague.

“Since May 2018 Canberra Metro has forecast the light rail date of operations commencement to be 21 December 2018. Indeed the most recent program received by the territory from Canberra Metro on 8 October 2018 still maintains an operations commencement date of 21 December 2018," the documents read.

“As such - notwithstanding risks identified by Transport Canberra in Canberra Metro’s program - until that time it has been appropriate for you in public discourse to make statements along the lines of 'Canberra Metro has advised it proposes to open the project in December'.

"Following from the above, Transport Canberra recommends that for the indefinite future you describe the expected light rail operations to date to simply be 'in early 2019'. You may also wish to note that the date is subject to third party accreditations [and] Canberra Metro will be able to provide greater clarity on the exact date closer to the end of the year."

That same day Ms Fitzharris's office contacted the media to advise that the start date would be pushed back into 2019.

The documents add weight to admissions from Under-Treasurer David Nicol during last year's annual reports hearings that the government had repeatedly asked Canberra Metro whether its construction program was achievable. At the time, Ms Fitzharris's office played down that there were any doubts about the program before the start date was delayed.

They also provide background as to why the minister will still not nominate a date for light rail to begin operations, even though it's due to start next month.

Recently, she said the service would begin running "on a Saturday in April".

The government has also said the light rail would be up and running when the new bus network goes live on April 29.

A government spokesman said Transport Canberra and the minister had been consistent and accurate in reporting both Canberra Metro’s program and the fact that risks exist with the program.

“In verbal conversations with Canberra Metro Transport Canberra officials reached the conclusion the next iteration of Canberra Metro’s program may not show a December opening date. Under the [public-private partnership] contract structure, it is appropriate for the territory to publicly discuss the opening date shown in Canberra Metro’s latest program,” the spokesman said.

”As soon as Canberra Metro’s program changed and no longer showed a December opening date, so did Transport Canberra’s advice to the minister and the minister immediately updated the Canberra community.”