A photo of the judge heading Quebec's corruption inquiry was yanked by the Parti Québécois hours after it was used in an attack ad against the Liberals.

The picture of Justice France Charbonneau, who has maintained she wants her inquiry to remain neutral during the April 7 election campaign, was prominent in the ad released on Thursday, the same day the province's political leaders were to have their first televised debate.

The ad on the PQ's Twitter page Thursday targets the Liberals and points to the number of times its current crop of candidates voted in the legislature against holding a corruption probe.

"Nothing has changed at the PLQ," reads the ad, which features photos of incumbent Liberal candidates.

It also cites the number 358, which the PQ says indicates how many times they voted against holding an inquiry.

For several hours, the ad also prominently included a photo of Charbonneau, the judge who heads the corruption commission and who shut down her inquiry because of the campaign.

But late Thursday, the photo was removed, although the rest of the ad remained intact.

Just two weeks ago, the commission insisted it wanted to be politically neutral and that it preferred to stay away from the political arena.

"Elections are the basis of democracy and the commission does not wish to influence voters one way or another," the inquiry said in a statement March 5.

It decided, therefore, to adjourn hearings until the day after the April 7 election rather than tackle sensitive subjects such as political party financing and contracts involving the provincial Transport Department.

Inquiry spokesman Richard Bourdon reiterated Thursday the inquiry wants to stay away from politics, but he could not say immediately if Charbonneau took issue with the advertisement or if the inquiry would seek a retraction.

The ad coincided with the PQ's move to attack the Liberals on the issue of integrity. The PQ has lost support in recent polls and the integrity issue was central to its 2012 election win.

During a news conference on Thursday, PQ candidate Bertrand St-Arnaud enumerated the scandals under the previous Liberal government and warned that any Charbonneau Commission recommendations would be shelved under the Liberals.

After much hesitation and under intense pressure, then-Liberal premier Jean Charest created the Charbonneau Commission in October 2011.

"I am sure that Quebecers do not want to go back to those dark years," said St-Arnaud, who served as justice minister in Pauline Marois' government.

The commission is expected to table a final report by April 2015.

Revised PQ ad France Charbonneau

The revised version of the advertisement erased Charbonneau completely.