Harper was asked about the issue on Saturday as he visited Ukraine, but he said little more other than the Senate is an independent body that is dealing with the problem itself.
An explosive audit of expenses that will be made public next week says there is little oversight and accountability in the upper chamber.
And auditor-general Michael Ferguson's report — sections of which were viewed by The Canadian Press — urges "transformative change" to fix systemic problems.
A total of 21 senators have been found to have made questionable expense claims and the RCMP is being asked to look at the expenses of another nine senators.
Harper says he views any abuse of taxpayer dollars by Parliamentarians to be unacceptable, but suggested the matter is out of his hands.
"The Senate is responsible for its own expenses, its own expense rules," Harper told reporters during a brief visit to Ukraine, where he stopped before attending the G7 summit in Germany.
Seven of the nine senators who have had their expenses referred to the RCMP are retired, including Liberal senator Rod Zimmer.
His disputed expense claims total 176-thousand dollars — including travel that auditors allege was for non-Senate business, and a housing allowance that he wasn't entitled to.
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