Peter Robinson defends the claims to BBC NI Political Editor Mark Devenport
MPs Peter and Iris Robinson claimed about £30,000 for food in parliamentary expenses over a four-year period, according to the Daily Telegraph.
Leaked expenses claims in the paper show the DUP couple claimed £160,000 in mortgage interest payments between 2004 and 2008.
These were claimed for an apartment owned by the couple in London.
Mr Robinson said the money was claimed legitimately but both he and his party believed the system needed reform.
"There's a world of difference between those who legitimately claim within the rules and those who are clearly operating outside the rules," he said.
"I'd be pretty sure that the amount that I actually spend would be more than that for which I have claimed."
He said whatever system was introduced some people would still not be happy.
Residents of Mr Robinson's constituency give their reaction to the claims
"I think if MPs slept on a park bench and starved themselves that would still be too much for some people," he said.
MPs are entitled to claim up to £400 per month in food bills while away from their main home on parliamentary business. Receipts are not required.
The newspaper states that the couple each claimed the maximum in most months.
Mr Robinson, NI's first minister, said that over the period his average weekly claim was around £70 which he said was not unreasonable for London.
The figure of around £70 for each of the Robinsons can be calculated by dividing the total claim of £30,525 by the number of days in four years (1406) which gives an average joint daily claim of around £10.50 each.
The Telegraph also reports that both Mr Robinson and his wife claimed around £1,200 for service charges on their London flat when they submitted a claim on 31 March 2007.
Mr Robinson's claim was rejected by a Westminster official as Iris Robinson had already made the claim. Mr Robinson said this was an innocent mistake.
"Over all the years there was one inadvertent claim prepared by the person who prepared the claims and it was because both claims were put in the same envelope and sent to the House of Commons.
"It was obviously something that would be spotted and happily it was," he said.
My party colleagues and I want reform and indeed have voted for change. Such steps are necessary in order to gain public confidence
On the same day each claimed around £5,000 for five months' mortgage interest payments.
This was also rejected and the reason stated was that no mortgage interest statements had been submitted to back up the claim.
It is not clear from documents whether the money was ever paid or whether the statements were submitted.
Mr Robinson said: "The claims were submitted consistent with House of Commons rules and after Fees Office advice.
"Many people hold the view that the rules for the payment of expenses should be changed.
"My party colleagues and I want reform and indeed have voted for change. Such steps are necessary in order to gain public confidence."
He said the Daily Telegraph had "bunched the claims of my wife and I together" and given a total over four years in order to arrive at a high figure for the food expenses.
However, Traditional Unionist Voice leader Jim Allister said public trust in politicians had been "rocked to its core".
"In Northern Ireland the added dimensions of double-jobbing and family-dynasty building, has added to the public contempt," he said.
"Paying the weekly grocery bill is a huge struggle for many, so when extravagance, at the public expense, is flaunted, it offends right-thinking people."
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