Instead, the embattled Mrs Bishop left it to her staff to check the details before it was published on the department’s website.

Mrs Bishop’s failure to check her own expenses occurred despite the form asking MPs to ‘‘please check the information detailed’’ as part of the regular reporting process and stating MPs must ‘‘certify that my use of each entitlement ... administered by Finance, was in accordance with the provisions legislated for each respective entitlement’’.

A spokesman for Mrs Bishop confirmed she had not checked the expense report and said ‘‘our office staff reconcile the report against the Speaker’s own diary to ensure the accuracy of the certification. Once we have done that we provide assurances to the Speaker that the report is correct and she signs the certification’’.

On Saturday, Mrs Bishop said she had  asked the department to investigate another two chartered flights she took to speaking engagements in Nowra and Young last year that may also have been fundraisers.

Mrs Bishop would not provide the details of Liberal fundraising events attached to her taxpayer-funded flights to Young and Nowra because it would be ‘‘improper to comment’’ while the  department investigated, her spokesman said.

Mrs Bishop maintained on Sunday the $5227 helicopter flight ‘‘was done within the entitlement. When I saw that figure, I saw it was too large and that’s why I’m repaying it’’.

But current and former MPs including Treasurer Joe Hockey, Environment Minister Greg Hunt, former treasurer Peter Costello, former leader John Hewson and former Victorian Premier Jeff Kennett all publicly criticised Mrs Bishop’s use of expenses on Sunday, though Prime Minister Tony Abbott was standing by his hand-picked Speaker 

Privately, anger within Liberal Party ranks was on the rise, with ministers and backbench MPs – none of whom wished to be named – conceding Mrs Bishop may have to quit to limit the damage to Mr Abbott and the government. 

One MP spoke for the more than a dozen contacted by Fairfax Media when he said that ‘‘the PM needs to tap her on the shoulder, but I don’t think he will. So she needs to resign, because we should be talking about Bill Shorten, not this’’.

A defiant Mrs Bishop made it clear on Sunday she does not intend to resign, or apologise, despite agreeing to repay cost of the charter flight, plus a $1300 penalty.  

She also defended a recent two-week trip to Europe that cost taxpayers close to $90,000, declaring: ‘‘It wasn’t $90,000, it was 88 [thousand]. Indeed the President of the Senate who led the delegation to exactly the same meeting, the 12 months before, spent $92,000. So it is simply the way that delegations are arranged.’’

Mr Hockey said it was sucking the oxygen from political debate.

with Rick Feneley, Gareth Hutchens, James Robertson