If Speaker Bronwyn Bishop had "nothing to fear" she should produce evidence that her taxpayer-funded travel to a colleague's wedding coincided with official business, says former committee colleague and Labor MP Kate Ellis.

Mrs Bishop has this week stood by a claim that a $600 return flight taken to Albury on the weekend of fellow Liberal Sophie Mirabella's wedding was in fact related to research for a parliamentary committee she chaired on work-life balance.

Ms Ellis – who also served with Mrs Bishop on the standing committee into family and human services in 2006 – argues that if the Speaker's trip was official travel, it would have been disclosed and noted in committee minutes.

"I do not recall the Speaker getting any approval for travel [to Albury],"  Ms Ellis said.  "I struggle to think of any reason why the chair would need to be there. But if she did it will be recorded very clearly in black and white.

"If the Speaker has nothing to fear I would encourage her to produce [committee] minutes.

"We should all be able to see that answer in black and white today."

A spokesman for the Speaker declined to produce minutes and disputed that her travel needed to have been approved. "Committee chairs are not required to seek approval," he said.

Mrs Bishop's office also declined to say if Mrs Bishop had reported back to the committee on her meetings, or produce a copy of the Speaker's diary.

Mrs Bishop arrived in Albury about 5pm on a Friday. She was in Wangaratta, about an hour's drive away, for the wedding on Saturday and back in Sydney by 3pm Sunday.

The Commonwealth Remuneration Tribunal says that MPs may claim travel for official business only for "properly constituted meetings".

Ms Ellis said the growing pressure on Mrs Bishop to provide details of her trip to Albury required intervention from Prime Minister Tony Abbott, who himself repaid travel expenses claimed to attend Mrs Mirabella's wedding and has described the Speaker as his political mentor.

"It's time for the Prime Minister and the Speaker to provide some clear answers," she said. "This is a matter for Tony Abbott and Tony Abbott's leadership [… and whether the PM] chooses to side with Bronwyn Bishop or the Australian public".

Fairfax has attempted to secure a copy of the 2006 minutes from the family and human services' committee secretariat but an official there declined to provide a copy of the documents, which do not appear to be publicly available.

The latest Essential poll, released on Tuesday, showed while 34 per cent of Coalition voters believe Mrs Bishop should remain in the position of Speaker, 25 per cent believe she should resign as Speaker or from Parliament. Another 30 per cent believe she should stand down while there is an investigation into her expenses.

Mr Abbott ducked questions on Monday about whether Mrs Bishop ought to repay the cost of travel entitlements claimed, even though he had taken a similar step two years ago.

Mr Abbott repaid $1100 in costs claimed for attending Ms Mirabella's wedding after seeking advice on the matter in 2013.

He then issued a warning to his fellow Liberal MPs to follow his example by repaying doubtful expenditure.

Ms Ellis' challenge comes after another former Labor MP on the same committee cast doubt on Mrs Bishop's story.

Jennie George told Fairfax she never recalled the Speaker speaking about any research or interviews conducted in Albury and found her explanation "mystifying".

Documents lodged with the Department of Finance in Mrs Bishop's own hand and bearing her signature affirmed that the purpose of her trip was "committee chair business"

According to the committee's final report on work-life balance released in 2006, the committee it held no public hearings or meetings in Albury or outside of capital cities.

with Fergus Hunter

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