OTTAWA -- Federal Liberals are dipping into their party war chest to advertise about government advertising.

The party has paid for prime-time NHL playoff real estate to lampoon the Conservative government's ubiquitous "economic action plan" promos that have been saturating the airwaves since 2009.

Opposition parties have long complained that the government ads are thinly disguised partisan propaganda -- paid for by taxpayers.

The cheeky Liberal ad purports to be a message from Prime Minister Stephen Harper, thanking Canadians for footing the bill.

It claims taxpayers have forked out $750 million over the past nine years to pay for government commercials -- a figure that includes all government of Canada advertising, including standard public service announcements as well as the more debatable ads that burnish the Conservative government agenda.

The Liberal party is paying -- it won't say how much -- to run its ad during the hockey playoffs and on social media.

Set to jaunty music, the minimalist ad features a series of written lines superimposed over the government's economic action plan logo.

"Enjoying the playoffs?" the script asks. "Enjoying all the government ads? Hope so. After all, you're paying for them."

It concludes with this message superimposed on the face of the prime minister: "Thanks, eh? You people are the best -- Stephen."

A senior New Democrat said the Liberal ad is "a bit rich" coming from the party that went on an "advertising extravaganza" when it was in power, culminating in the sponsorship scandal.

"The evidence shows they are as bad as the Conservatives when it comes to using public money for partisan advertising," said Karl Belanger.