Opposition MPs aren't the only ones making Bev Oda's spending habits a thorn in the government's side – her own colleague, Conservative MP John Williamson, is also raising them as a point of contention within their caucus.

Williamson used to head the Canadian Taxpayers Federation and was also Prime Minister Stephen Harper's director of communications before he stepped down to run for his New Brunswick seat.

He confirmed to CBC News that he brought up the minister of international co-operation's travel and hospitality expenses behind closed doors at a weekly Conservative caucus meeting. Williamson would not elaborate on what he said, citing caucus confidentiality.

A spokesman from his office, however, said that what Williamson told the caucus could be taken in the context of his previous job with the CTF – an organization that advocates on behalf of taxpayers.

The CTF, according to its website, dedicates itself to lower taxes, less waste and accountable government. It created the annual "Teddy Waste Awards" to highlight government waste, named after a public servant who was fired over his expenses.

Conservative MP John Williamson has raised the issue of Bev Oda's spending practices within the Tory caucus. (House of Commons)

The displeasure with Oda from within her own ranks adds to the opposition's demands for her to be more accountable.

There was a call for her to be fired on Friday, from Liberal MP Mark Eyking, who called Oda an "embarrassment to Canada."

"Yesterday we learned that she changed her public travel expense claims with no explanation. Is the minister ready to admit that there are more $16 glasses of orange juice that she has charged to taxpayers? When will she be accountable for her bad behaviour?" he said during question period.

"Our government is committed to keeping expenses of ministers travelling at a reasonable cost to taxpayers," House leader Peter Van Loan responded. "That is why they are much lower than [what] the honourable member's party spent on ministerial travel when it was in government. In the case of the minister in question, all inappropriate costs have been repaid."

Eyking said Oda can't be trusted to manage her own travel expenses, let alone Canada's foreign aid and development budget.

"I don't know what's wrong with the prime minister, why doesn't he just can her? Fire her. What is he waiting for? The middle of the summer when no one's watching on the Hill to do a cabinet shuffle?" he said after question period.

Opposition wants Oda to testify at committee

Eyking said Oda should explain in front of a parliamentary committee why her travel expenses have so often been amended, according to the proactive disclosure section of her department's website. Ministers are required every quarter to post summaries of their travel and hospitality expenses and those of their staff.

The NDP also wants to see Oda before a committee. It plans to request the appearance of Oda and Foreign Affairs Minister John Baird at Monday's foreign affairs committee meeting to talk about their departments' estimated spending. The NDP says Oda would get questions about her personal spending habits "for sure."

The CBC reported Thursday that Oda's office is refusing to answer whether she has paid taxpayers back for any other inappropriate travel expenses in addition to the ones from April. A Canadian Press story revealed that when she was in London last June she stayed at the swanky Savoy hotel – costing more than $600 per night – instead of the less expensive hotel she was booked at, and Oda hired a car and driver costing about $1,000 per day. An orange juice that cost $16 was also among the charges.

She ended up reimbursing the government $4,025.26 after the story broke and apologized for charging the "inappropriate" costs to taxpayers.

The entry for her London trip has since been amended on the proactive disclosure page on the website, but that's not the only change.

Expenses for trips to Haiti, East Africa and Korea over the last year have also been changed at some point after they were originally posted online. An asterisk beside the amount indicates it was modified.

It isn't clear from the website when, how, or why each amount was changed, and Oda's office won't provide explanations. All Oda's spokeswoman would tell CBC News is that they were reviewed "in the interest of accountability." Some entries, for Oda and some of her staff, were modified months ago.

It's not just expenses for trips in 2011 and early 2012 that were amended, some in 2009 and 2010 were also adjusted after they were originally filed.

For example: the airfare, transportation, accommodation and meal expenses for a 2009 visit to Mozambique and South Africa – total cost $13,255.11 – were also amended after they were first posted online.

There could be accounting errors or other reasons why proactive disclosure entries are later changed, but Oda didn't explain when asked in question period Thursday and her office didn't answer repeated requests to provide the information.

The responses from Oda and Van Loan on Thursday and on Friday don't make it clear whether she has paid back inappropriate expenses for only the London trip or other trips. Both of their offices were asked for clarification and they did not provide any.