The inquiry was responding to the use of Justice France Charbonneau's image in a Parti Quebecois ad that attacked the Liberals' integrity.
The ad appeared online Thursday on the PQ's Twitter feed.
Charbonneau's photo quietly disappeared late Thursday, but not before it had been shared over several hours and criticized online.
The inquiry said in a terse statement Friday it has never allowed the use of Charbonneau's photo and it called on political parties to keep her and the inquiry out of their partisan material.
"The commission of inquiry wishes to state it has not authorized and will not authorize any political party to use its image or that of its president for partisan purposes," the statement said.
PQ Leader Pauline Marois said she was satisfied her party rectified the situation.
"You know, nobody is perfect," Marois responded when asked about the photo Friday. "As soon as they realized it wasn't pertinent, this photo was withdrawn."
The image was online for most of the day and was shared by party staff and supporters before disappearing in the evning.
"I'm satisfied that we did this quickly," Marois said.
The image was used despite a message from Charbonneau just two weeks ago that her inquiry wishes to remain neutral during the campaign leading to the April 7 election.
The rest of the PQ ad remained intact Friday, with the words "Nothing has changed at the PLQ." It draws attention to the number of times the current crop of incumbent Liberal candidates voted in the legislature against holding a corruption probe.
The PQ made no mention on its own Twitter page as to why it removed Charbonneau's image.
A spokesman for Elections Quebec said it couldn't accept a complaint concerning the matter.
"(Advertisements) on Twitter don't cost anything so we cannot consider this as an election expense," said Denis Dion.
The inquiry reaffirmed in its statement Friday it is apolitical and independent.
Staying neutral was behind the commission's decision to adjourn hearings until the day after the April 7 election rather than tackle sensitive subjects that could have an impact on the outcome.
Outstanding issues like political party financing and contracts involving the provincial Transport Department will be dealt with in the coming months.
The commission is expected to table its final report by April 2015.
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