The Public Works Department is supposed to prepare a report each year on how the government manages its advertising, including the major campaigns undertaken and the amount of money spent on ads.
But the last report posted on the Public Works website is from 2009-10. It highlighted campaigns under the governing Conservatives' Economic Action Plan umbrella and the response to the H1N1 flu pandemic.
The department won't say when the 2010-11 and 2011-12 reports will be released.
"We anticipate that the 2010-2011 report will be published soon," Public Works spokesman Sebastien Bois said in an email.
Public Works needs to gather and validate information from media suppliers across the country and other government departments before it can complete its annual advertising report, Bois said.
"This process can take considerable time given the validation, consolidation and consultations required with multiple stakeholders."
Bois could not say precisely when the report would be available.
"We are unable to provide you with a specific release date for the 2010-2011 government of Canada annual report on advertising activities, given the significant number of stakeholders involved in the process of confirming and approving the expenditure data included," he said.
"Publication dates vary from year to year depending on the complexity of the report."
The federal New Democrats say the government's failure to release the advertising reports fits a pattern of the Conservatives withholding information.
"It just reeks of hypocrisy," said NDP MP Linda Duncan, the party's public works critic.
"The whole reason why they took the Liberals down was accountability, right? Of course, they keep reneging on every promise."
The last report posted online shows the government spent $136.3 million on advertising between April 2009 and March 2010.
More than half that money was spent on two campaigns: the Economic Action Plan, which cost $53.2 million, and the H1N1 flu pandemic, which cost $24 million.
Government spending on advertising has fluctuated over the last decade.
The previous Liberal government spent $111 million on ads between April 2002 and March 2003. But the government spent significantly less in subsequent years after Ottawa froze all federal advertising in the wake of the Liberal sponsorship scandal.
Prime Minister Stephen Harper's Conservatives spent $86.9 million between April 2006 and March 2007, their first full fiscal year in power.
Ad spending fell slightly to $84.1 million the following fiscal year, and dropped again to $79.5 million in 2008-09 — although a two-month ban on advertising during the 2008 federal election likely contributed to that decrease.