The Ontario NDP has written to provincial chief electoral officer Greg Essensa, asking him to investigate an ad by Ontario PC leader Patrick Brown’s byelection campaign that they say may violate political advertising rules.

A half-page advertisement from the Brown campaign appeared on page A2 of Wednesday’s edition of the Orillia Packet and Times. The byelection takes place on Thursday.

Ontario’s Election Finance Act prohibits all political advertising on election day and the day before an election day. Brown, formerly a Conservative MP for Barrie, is seeking to gain a seat in the Ontario legislature after winning the provincial party’s leadership race in May.

 “As political advertising is prohibited during the campaign blackout period, we formally request that this matter be investigated and proper action be taken,” Karla Webber-Gallagher, provincial secretary of the Ontario NDP, wrote in a letter sent to Essensa on Wednesday.

Brown’s campaign spokesperson, Tamara Macgregor, said they’re “looking into” the placement of the ad in the paper, which had a paid weekday subscription base of 9,100 in 2013.

“(The campaign) will respond to any correspondence they receive from Elections Ontario.”

An Elections Ontario spokesperson told the Barrie Examiner Wednesday that they would not confirm whether they have received a formal complaint about the ad, as it could give an unfair advantage to another party.