After years of advocating for smaller, more efficient, government the Productivity Commission itself appears to have been outsourced.

Government officials have testified at a public hearing in Canberra that there was no need for the Productivity Commission to scrutinise Australia's biggest ever trade deal - despite it being the kind of job the commission was created to do.

Elizabeth Ward, a first assistant secretary for the Department of Foreign Affairs and Trade, told members of Parliament on Monday that there was no point asking the Commission to model the Trans-Pacific Partnership.

The TPP is a huge trade deal involving 12 countries in the Pacific region, including Australia.