Federal government departments are spending eye-watering sums to know what the public is thinking and what the media is saying about them, new documents show.

In some of the more surprising disclosures, the Department of Defence is spending more than $500,000 a year on pay TV and, between July and October 2014, splashed $454,125 - or about $5000 a day, on newspapers, magazines and other publications. Another department also spent nearly $90,000 on books over four months.

Tony Abbott's government departments are spending eye-watering sums to know what the media is saying about them. Credit:Daniel Munoz

A Fairfax Media analysis of the documents also shows seven departments splashed a combined $1.2 million on "market research" - in many cases focus groups and polling - in just four months. Dozens of government agencies are yet to respond to formal requests to reveal how much they also spent, suggesting the total bill is likely to be far higher.

For example, the Department of Defence refused to disclose how much it spent in market research between July and October but the bill for 2013/14 came in at $2.2 million.