Changes to Northern Ireland's licensing laws could cost police £7m in overtime, a Stormont committee has been told.
The figure is contained in a letter sent to politicians examining a bill for reforming licensing laws.
The changes would extend late-night opening hours and are contained in proposed new legislation which is at committee stage at the Northern Ireland Assembly.
Police said changes to shift patterns would have to meet EU working rules.
MLAs have previously taken evidence from a range of interested bodies, including senior Police Service of Northern Ireland (PSNI) figures.
The letter to Stormont's Communities Committee said that extensions to opening times would mean changes to shift patterns and overtime for PSNI staff.
The service estimates the new costs would be "challenging".
DUP MLA Robin Newton who sits on the committee said the estimate from the PSNI was a "significant amount of money" at a time when its budget was under considerable pressure.
He said the committee must express its "concerns" about the figure.
fellow DUP MLA Paula Bradley, who chairs the committee, said it was surprising that the issue had not been raised before.
She said it was important that the effect on the PSNI budget would be part of the committee's review of the planned licensing changes and would be part of its report.