Audit says sell Aust Post, NBN

The nation's postal service heads a list of government-owned enterprises the national commission of audit says should be privatised.

Others on the sell-off list include Snowy Hydro, the Royal Australian Mint and the national broadband network.

The commission says about $13 billion in capital is locked up in government-owned bodies.

While the states have been selling some of their assets, especially electricity generators, privatisation has been a mostly dormant issue at the federal level, it says.

The commission cites a rapid decline in letter volume as one of the reasons for not needing Australia Post to be in public hands.

It recommends the corporation be sold off after 2016, three years after the UK went down the same path with the Royal Mail.

AMP chief economist Shane Oliver said there would be healthy demand from the private sector.

"You would probably get quite a lot of money for Australia Post," he told AAP.

"There's no reason why a private contractor wouldn't run it.

"Its role is changing. You can envisage a point in the future when the whole service is being done by parcel services like UBS or FedEx.

"I imagine there would be a lot of interest in the real estate as well."

However, unions are opposed to privatising Australia Post, warning services and jobs would be lost.

"Rural and regional communities and small businesses who rely heavily on the diverse range of services delivered by Australia Post would be hit the hardest," CEPU Postal and Telecommunications NSW branch secretary Jim Metcher said.

Dr Oliver said the private sector would also be interested in assets such as Defence Housing Australia, the Australian Rail Track Corporation and the mint.

But NBN Co was a different story.

"That would be a difficult one. Most private sector companies would likely say that one's too messy," Dr Oliver said.

The commission has not nominated a timetable for privatising NBN Co, but it has noted that provisions are already in place.