Update 3.38pm: Presidential Candidate Joan Freeman says she is shocked by the fact that €317,000 in spending by the president's office is not subject to an audit.
The revelation about the Áras accounts came at yesterday's Public Accounts Committee.
Senator Freeman said it was "mind-boggling" that some people were defending the practice.
"I'm shocked to hear that €317,000 of public money is paid every year without audit, without checks and without accountability," she said.
"I know of no other public money that is treated in this way, and to find people actually defending it is mind-boggling. On what possible grounds could you defend this level of secrecy?"
She called for public spending to be transparent.
"As someone who has worked in the voluntary and charity sectors for years, I'm disappointed at the double standards in the way scrutiny is applied to public monies.
"That is not the case here and we should be told what this budget is needed for, why it hasn't been accounted for and why no-one bothered to ask questions until now."
By Fiachra Ó Cionnaith
Update 2.43pm: Two Government ministers have accused rival politicians of "showboating" and attempting to reduce the presidential election to a competition for "who will stay in the cheapest hotels" amid growing questions over spending levels in the office.
Health Minister Simon Harris and Housing Minister Eoghan Murphy lashed out at the situation this morning, saying the timing of the sudden interest is politically motivated "attention seeking" that is designed to "damage" Michael D Higgins's re-election bid.
Speaking after the Dáil's public accounts committee was told on Tuesday the presidential office receives €317,000 in an unaudited allowance every year for hospitality reasons, Mr Harris and Mr Murphy accepted there is a need for greater transparency.
However, the two senior Government ministers insisted there has been no indication of any wrongdoing and that it is entirely misleading to suggest Mr Higgins has done anything untoward in his position as the money is used to welcome guests to the Aras.
"I think there is an attempt by some and probably some who are not supporting Michael D Higgins to try to suggest there is something inappropriate, improper or unexplained in all of this," Mr Harris said.
"My understanding from listening to the comments from President Higgins' spokesperson is this is an allowance given to previous presidents and that it's largely an allowance used for funding events that have been of value where different groups are invited to the Aras and thanked by the president and Mrs Higgins for their contribution to Irish society.
"I think the showboating that we see going on from some in the PAC is growing a little weary.
"It's absolutely important that there is full transparency, I used to be a member of the PAC as did Minister Murphy, I think it's absolutely appropriate that there is full transparency. But I think there is a yearning to try and create something at the PAC now and link it to President Higgins, and the electorate will see right through that," he said.
Mr Harris said while the PAC has an "important job to do" it is vital the Oireachtas financial watchdog does not "just bark at every passing car" and confines its work to legitimate issues.
However, pressed on the lack of presidential spending transparency after claiming the current questions are "a desperate, partisan, political attempt" to "damage" Mr Higgins that amounts to "attention seeking", Mr Harris added: "I personally don't think there should be an issue with the PAC asking questions about all taxpayers money once there's a line they don't cross about questioning the decisions made by the president of Ireland, because the constitution's clear on that.
"But I just feel it would've been useful if the members of the PAC who were so keen to raise this, were just as eager to do it last year or the year before."
At the same media event to launch a new Housing First initiative in Dublin city centre Housing Minister Eoghan Murphy mirrored Mr Harris's comments, saying people need to keep "our eyes and ears open to the timing here".
"The presidential campaign is a very important part of our country's democracy, it doesn't happen very often.
"We want this campaign to be about vision and values, we don't want the opposition or any other people try and reduce it to who will stay in the cheapest hotels, it should be about a person's vision and values, and we should focus on that.
"That [the €317,000 allowance revealed by the PAC on Tuesday] is a separate question that shouldn't have even been asked, people politically are trying to link it to Michael D, that's what's going on here.
"PAC didn't even take legal advice before inviting in Martin Fraser, so I think the PAC needs to be very careful and we need to walk into this with our eyes open to see what people are potentially trying to do here.
"They're potentially trying to damage the incumbent at the beginning of a campaign and also another risk which would be reducing a very very important national debate over the next number of weeks to more trivial issues that aren't worthy of the more important things we need to be talking about today in our country, like homelessness."