Housing Minister Phil Heatley admitted to The Dominion Post that he had bought $70 worth of wine on his card for National Party colleagues at AMI Stadium in Christchurch last year.
He said he would refund it after checking with officials and finding the purchase should not have been made.
Energy Minister Gerry Brownlee is also checking whether $151 spent on a lunch for electorate staff paid for on his ministerial card went against rules and should be refunded.
Mr Heatley said he had on a few occasions paid for goods on his ministerial card and later reimbursed Ministerial Services, but the newspaper has questioned why such purchases were being rubber stamped.
Internal Affairs said queries about the issue needed to be sent to the department through an Official Information Act request.
MPs' and ministers' expenses came under intense scrutiny last year with the first ever disclosure of the MPs' claims for travel and housing expenses.
Some MPs paid back tens of thousands of dollars spent on housing in Wellington and travel for themselves and their partners.
Prime Minister John Key ordered a review of housing allowances which resulted in spending rules being simplified and limited.
