The Federal Opposition claims Prime Minister Malcolm Turnbull's "exciting time" catchcry has been removed from the Government's Ideas Boom website to hide a possible breach of advertising guidelines.

Labor last month referred the $28 million ad campaign promoting the innovation agenda to the auditor-general, saying its use of the "exciting time" phrase was party political.

Until at least February 28 the Ideas Boom homepage prominently featured: "There's never been a more exciting time to be Australian."

But by early March the slogan on the website front page had been replaced by: "Welcome to the ideas boom."

The original slogan had been changed to "Welcome to the Ideas Boom" ( Innovation Department )

Labor's waste watch spokesman Pat Conroy said the Government had questions to answer.

"What's become apparent after I wrote to the auditor-general [on February 15 is] that content was hidden on their website," Mr Conroy said.

"What they've clearly done is try to hide the slogan, tried to hide the content in a vain and very desperate attempt to deflect attention from what I consider a possible breach of their advertising guidelines in this $28 million wasteful advertising campaign.

"They're desperately trying to hide their misuse of taxpayers' money to advertise a political slogan of Malcolm Turnbull's — or they're just not excited anymore."

The design of the website has since been overhauled.

Mr Conroy has lodged a Freedom of Information request seeking more details about the change.

Innovation Department says website 'undergoes regular updates'

A spokesman for the Innovation Department downplayed the language shift.

"The National Innovation and Science Agenda website undergoes regular updates to support and reflect the latest phases of the advertising campaign," he said.

The Innovation Department said "exciting time" still featured in the official innovation agenda report, where it is the first line in the form: "There has never been a more exciting time to be an Australian."

The "exciting time" phrase also features in a television advertisement.

The Ideas Boom campaign is running across television, online, social media and print, with the Government saying it will help drive a cultural shift in Australia.

The advertising blitz came after the $1.1 billion National Innovation and Science Agenda was launched last December.