Public servants have been slammed for failing to properly reveal the costs of an overpriced plan to replace luxury travel trains in Queensland.

An auditor-general report, released on Tuesday, describes the Sunlander 14 project as "a case study in obfuscation and ill-informed decision making".

The project, approved in August 2011 by Opposition Leader and then transport minister Annastacia Palaszczuk, sought to deliver three 14-car trains through acquisitions and upgrades for $195 million.

The report found the 14-car trains were too big, with market research not supporting Queensland Rail's expectation that luxury train travel would attract higher-paying customers.

It also noted that, by 2012, the cost of the Sunlander 2012 project had ballooned to between $358 and $404 million - about twice what had been approved.

Auditor-General Andrew Greaves found public servants involved in the project either ignored or did not want to advise the government on the true costs to begin with, and instead offered more "palatable portions".

"We could not establish whether information was withheld intentionally: the distinction is important, as it is the difference between maladministration and possible malfeasance," Mr Greaves wrote.

He said there was a failure to communicate effectively from the project's inception until the time the Liberal National government sought to reduce the project to three nine-car trains in June 2013.

Transport Minister Scott Emerson pointed the finger at Ms Palaszczuk, saying it was scandalous that she did not ask further questions.

"This shows that she was either asleep at the wheel or ignored the basics," Mr Emerson told reporters.

He said the government had overhauled QR's senior management and board.

But Ms Palaszczuk hit back, saying Mr Greaves clearly levelled blame at public servants.

"If you are not provided that advice, you cannot act on things you simply do not know about," she said.

Ms Palaszczuk also highlighted Mr Greaves's criticism of the LNP government after it issued a media statement announcing it had saved "almost $50 million" by reducing the scope of the project.

"It is a false economy to 'save' $50 million when this means writing off over $50 million already spent or committed," the report says.

Mr Emerson said all three nine-car Spirit of Queensland trains would be operating by the end of December, on time and with a $204 million budget.

© AAP 2014