Internal documents seen by Fairfax Media reveal preparations have been made to create a separate legal entity for courier operation StarTrack and the parcels business, and to clean up its financial records – important groundwork for any future sale.

The postal workers union fears Australia Post is preparing for a sale, and Fairfax Media can reveal that late last year senior Australia Post finance staff were already working on a restructuring operation called "Project Bridge" to update internal financial reporting systems.

According to the documents seen by Fairfax Media, one benefit of Project Bridge is that it "enables financial management of two legal entities by July 2016". And it "enables a future simplified separation program" and "could be used if ownership separation is accelerated".

The overall goal of the financial overhaul is to "enable M&A (merger and acquisition) agility and commercialisation options".

Communications Workers Union spokesperson Joan Doyle, whose union represents posties, said she had been told "there was a high-level committee working on privatisation" inside Australia Post earlier this year. But the outcome of the work was not clear, she said.

Any decision to sell rests with the Finance Minister, Mathias Cormann, who told Fairfax Media that there were "no plans" to privatise. During the 2016 election campaign Prime Minister Malcolm Turnbull said privatisation of the publicly owned company was not on the agenda because it was not ready.

Fairfax Media understands that those working on Project Bridge received recommendations that the accounts of StarTrack and Parcels Post be combined and consolidated into one new accounting platform, and that Australia Post create a new legal entity for StarTrack and Parcels Post.

A spokeswoman for Communications Minister Mitch Fifield said Australia Post was responsible for its internal operations.

"As we have consistently said for a very long time, the government has no plans to sell Australia Post either in full or in part. Nothing has changed," the spokeswoman said.

The proposals put forward in 2015 would cost up to $60 million over several years and include up to 144 redundancies, primarily in the finance department.

An Australia Post spokesman would not say whether the proposals were fully adopted, but confirmed financial systems have been updated.

"Privatisation is not a matter for Australia Post," he said.

"While the vast majority of integration activities have been completed, we continue to look for efficiencies and synergies within our business. This includes looking at our back office support functions but there are no plans for forced redundancies. There is also work under way to update our accounting systems, which are up to 20 years old."

Australia Post has reported StarTrack's financial performance as part of its parcels business since becoming full owners in 2012, he added.

Post's profitable parcels business currently cross subsidises the loss-making letters business. In recent years the letters business' revenue was about $1.7 billion, but costs $2 billion to operate.

In 2014-15 Australia Post's revenue was $6.3 billion with a post-tax loss of $222 million, largely due to restructuring costs.

Parcels services accounted for $3.2 billion of revenues and earnings of $240 million. Parcel Services includes StarTrack, freight forwarding operations and all Express Post products.

Last month Australia Post reported revenues for 2015-16 were $6.6 billion with a post-tax profit of $36 million. Parcel profits were up to $314 million while letters' loss was $138 million.

Detailed financial information won't be available until its annual report is tabled in Parliament.

During the election debate Mr Turnbull said privatisation was "not on the agenda".

"Have you looked at the accounts of Australia Post? I think it's a long way away from being able to be sold," he said during the leader's debate on May 13.

"I see no prospect whatsoever of Australia Post being privatised or being 'privatisable' within the next term of government; what happens in the far off future, who knows?"