JULIA Gillard has lambasted the media for not exposing the up to $10.6 billion black hole that Treasury found in Tony Abbott's election costings.

She has also taken an oblique swipe at some of News Ltd's coverage.

The Prime Minister said the campaign contained a lesson for media organisations.

The central issue had been the economy - the government's stimulus versus Mr Abbott's slogans about debt and waste. But ''it took three independents to find the $11 billion black hole. That should have been a job done by journalists during the campaign. People should have known that before they voted'', she told the ABC. ''The biggest story of the campaign was effectively missed''.

The independents got the information after the election because they insisted Treasury should cost both sides' promises as part of their negotiations with them. Mr Abbott, who had earlier refused to submit his policies for official costing, eventually agreed to do so.