Sussan Ley maintains she's done nothing wrong despite stepping aside as health minister pending an investigation into her use of taxpayer-funded travel.

Prime Minister Malcolm Turnbull has ordered an investigation into the embattled minister's travel claims by the secretary of his department Martin Parkinson, insisting she will forgo ministerial pay until it's complete.

"I expect the highest standards from my ministers in all aspects of their conduct, and especially the expenditure of public money," Mr Turnbull said in a statement on Monday.

Cabinet secretary Arthur Sinodinos will step in as acting health minister.

Ms Ley fronted the media for the first time since the scandal over her taxpayer-funded trips to the Gold Coast broke last week, insisting she had nothing to hide and was hopeful of returning to the portfolio.

She dismissed the scandal as a distraction to the government's agenda but admitted she hadn't been able to ignore the intense interest and speculation.

"I'm very confident that the investigations will demonstrate that no rules were broken whatsoever," she told reporters in Albury.

Monday's announcement follows revelations Ms Ley bought a $795,000 apartment from a Liberal National Party donor during a taxpayer-funded trip to the Gold Coast in 2015.

It's also been revealed she claimed travel costs to the Gold Coast for New Year's Eve celebrations in 2013 and 2014 with one of Australia's richest women, Sarina Russo, founder of recruitment agency Job Access and a Liberal Party donor.

Ms Ley said she flew to the Gold Coast at taxpayers' expense at the invitation of a "prominent Queensland businesswoman" for a business lunch on New Year's Eve in 2013 and then another New Year's Eve event in 2014.

Ms Russo says she supports Ms Ley's statement and is happy to help the investigation.

"I respect and admire the Minister. She has worked diligently in every portfolio and has made a difference," she said in a statement.

"Every time I met with her it related to her portfolio or the government at hand."

After initially dismissing the purchase of the apartment as an impulse buy, Ms Ley admitted on Sunday it was an "error of judgment", vowing to pay back expenses for the trip.

She has asked the Finance Department to review all of her ministerial travel to the Gold Coast and will adjust her claims for another three trips there.

On Monday, she insisted her trip to the Gold Coast on May 9, 2015 to meet with a cancer patient about access to medicines was booked in before her husband told her about the apartment the night before the auction.

A taxpayer-funded car was booked to take her from Brisbane to her Gold Coast hotel, then to the auction "two minutes away".

Acting opposition leader Penny Wong said Ms Ley should have been sacked from cabinet, but Mr Turnbull had taken the "weak" option.

Former veteran Liberal Bronwyn Bishop, who was forced to resign as Speaker in 2015 after chartering a $5000 helicopter from Melbourne to Geelong for a Liberal fundraiser, defended Ms Ley and expressed disappointment that more colleagues hadn't publicly supported her.

Mrs Bishop said male MPs facing similar allegations seemed to get away with it and suggested Ms Ley's staff were responsible.

"My travel was arranged by my staff, as they're paid to do, and I can only imagine Sussan Ley's travel was done in exactly the same way," she told Sky News.

She said Ms Ley was being attacked by "people behaving like a pack of dogs", blaming socialists she claims are out to attack free enterprise.