Not time to sell off Aus Post: Leigh

Federal Labor does not believe in selling off public assets "willy nilly" just to balance the budget, shadow assistant treasurer Andrew Leigh says.

That means it's not time to put up the "For Sale" sign on Australia Post, even though its bottom line is taking a massive hit from the diminishing use of letters, he says.

Labor doesn't see asset sales as something that should simply be done to find a "cheap backdoor way" of balancing the budget, he says.

"We believe that assets ought to remain in public hands if there is a strong public case for it," Dr Leigh said during a speech at the National Press Club in Canberra on Tuesday.

"The notion that you would willy-nilly sell-off public assets in order to try and better the budget deficit is not one that Labor supports."

Dr Leigh used his address to release a discussion paper on the shared economy - using the internet to promote services that make efficient use of the world's existing stock of bedrooms, cars and tools.

He said Australia had a housing affordability crisis, yet there were nine million spare bedrooms across the nation.

"Some of our major cities are in gridlock, yet the majority of cars carry only one person.

"Many people own a power drill, yet use it less than an hour a year."