Northern Ireland's local government auditor is to hold a review into a dinner hosted by North Antrim MP Ian Paisley.
It will focus on £1,500 paid by Mid and East Antrim Borough Council for a table at the event, which was attended by senior Westminster politician Michael Gove.
The Electoral Commission has also said it was aware of the matter and was considering it in line with its enforcement policy.
A statement from the Northern Ireland Audit Office said: "We are aware of that particular issue and will specifically review that transaction as part of our audit procedures when we come to review the accounts."
Mr Gove is a senior Conservative and the UK's Environment Minister.
The DUP is propping up Theresa May's minority Government at Westminster on key votes.
Antrim Council has said the money was paid to Tullyglass Hotel, Ballymena, where the dinner was held, and not to the DUP.
A Mid and East Antrim Borough Council spokeswoman said the council received an invitation to a North Antrim Annual Business and Community dinner hosted and facilitated by Mr Paisley, with Mr Gove as special guest.
She added: "Elected members at full Council in August 2017 agreed to purchase this table and the event was attended by elected members from different political parties, senior officers and representatives from the agri-food sector across the Borough.
"Council was requested to make payment to The Tullyglass Hotel and did so via electronic payment. No money was exchanged between Council and the DUP."