Bronwyn Bishop’s office claims she has to keep secret her meetings in Albury on the weekend she claimed travel expenses to attend Sophie Mirabella’s wedding.

Bishop has been under increasing pressure to produce documentation to prove she was travelling on committee chair business on the weekend she claimed $755.06 in travel expenses while also attending former Liberal MP Mirabella’s wedding in Wangaratta in June 2006.

Bishop was chair of the standing committee of family and human services at the time and had to attend hearings of the balancing work and family inquiry.

A spokesman for Bishop’s office said that on the weekend in question she had to meet people in the area on an anonymous basis because they did not want to attend public hearings of the inquiry. When asked how many people Bishop met and what date the spokesman said he was not going to go into the details of Bishop’s diary.

Asked what rule that came under the spokesman said 3.25 in the travel allowance determination which says: “The chair of a parliamentary committee shall be paid travelling allowance in respect of each overnight stay in a place other than his or her home base when travelling on Parliamentary Committee business.”

Bishop did not claim travel allowance on the weekend, just her flights and a taxi.

The determination does not specify rules around the chair travelling alone and meeting with people anonymously. The standing orders for committees do not specify rules about chairs meeting with people anonymously but does say committees can hold private hearings.

Three committee members have to be present for it to constitute a committee meeting.

The expense claim was first reported in 2013 and Tony Abbott was among the MPs who attended the wedding and repaid the money. Bishop did not, maintaining she was on parliamentary business. Freedom of Information documents show Bishop wrote that she was attending to committee chair business in her documentation for the finance.

The standing committee of family and human services delivered three reports in that parliamentary term that Mirabella’s wedding took place in, between 2004 and 2007.

Not one public hearing or meeting for any of the inquiries was listed as being held in Albury or Wangaratta but the chair can travel on behalf of the committee if the committee authorises it.

Pressure is mounting for Bishop to reveal official documentation justifying the trip with the latest Essential poll revealing Bishop does not have public support on the issue. Only 19% of voters believe Bishop should stay on as speaker. Of Liberal and National party voters, 34% think she should remain in the job.

According to the FOI documents Bishop arrived in Albury at 4.45pm on the Friday and returned to Sydney on a 1.40pm flight on the Sunday.

Labor’s spokeswoman for education and early childhood, Kate Ellis, was also on the committee and said if there was an official committee reason for Bishop to be in Albury that weekend then documentation would exist.

“I can’t recall any reason Bronwyn Bishop would need to be in Albury that weekend but I do absolutely say if there was a reason, if she did go through the proper processes, then there would be documentation and we wouldn’t need to be here speculating about it,” she told reporters on Tuesday.

“This is up to Tony Abbott and Bronwyn Bishop to put this matter to rest and they should be able to do that very easily by just producing the documents.”

Bishop was put on “probation” by the prime minister after it was revealed she charged a $5,000 helicopter ride to a Liberal fundraiser to the taxpayer.

Another committee member from the time, the former Labor MP Jennie George, has said the committee did not have official business in the area.

“There was no decision of the committee authorising the chair to attend meetings in Albury,” she told Fairfax Media.

“We never heard a report back. If it was formal committee business it would be recorded. I’m mystified.”

Former Liberal MP Alan Cadman also served on the committee but said he has not kept records from the time.

“At that point [I was a] member of number of committees at that time and there were public hearings all over the country, I couldn’t possibly remember that,” he said.

A spokesman for Bishop said all travel taken by Bishop as committee chair was in accordance with the rules.

