LGBT activist Fred Karger told a packed news conference in downtown Salt Lake City a week ago of his plan to run cable ads on Comcast in Utah TV markets seeking insider tips on the Mormon Church that could be used to challenge the church's tax-exempt status.

In the ad, former young Mormon Church members — who answered a casting call in Utah — ask viewers to help them uncover the church's "vast business holdings" and "secret political activities," directing tipsters to

"I was assured repeatedly by our media-buying company that the commercial was cleared by Comcast's legal and technical [departments] and good to go," said Karger, who has fought the Mormon Church for years over its policies on gays.

Apparently, he wasn't good to go.

Instead of televising the ads, Comcast blocked the $2,000 ad buy in Logan, Ogden, Salt Lake City, Provo, and St. George a day after the news conference, contending that the cable company would not air advertisements "demeaning to individuals or organizations."

Comcast, one of the biggest sellers of local advertising in the nation, also told Karger that he was making unsubstantiated claims in the 30- and 60-second ads — an argument that Karger rejects. The dispute is now what amounts to a stand-off between Karger's small LGBT advocacy group, Rights Equals Rights, and the Philadelphia company's advertising division, Comcast Spotlight.

Comcast Spotlight spokeswoman Tara Hunter said on Tuesday that the division "reviews ads on a case-by-case basis for compliance with our guidelines. Upon review, the ad did not comply with our guidelines because the client was unwilling to provide substantiation for their claims and we do not accept ads that demean individuals or specific organizations. We offered to review any additional spots the client was interested in airing."

This isn't the first time Comcast has faced criticism over apparent ad blocking. Comcast nixed a cable ad last fall on a ballot initiative favoring a corporate tax hike in Oregon.

The pro-tax Oregon cable ad mentioned Comcast by name. As a corporation, Comcast opposed the tax hike and had put hundreds of thousands of dollars into the effort to defeat it. Comcast aired other pro-tax ads that did not mention its name, published reports said. Oregon's Measure 97 failed in the election.

Karger, who is based in California, says that the Mormon Church discriminates against gay Mormon couples and their children, and he rejects the idea that he was asking Comcast to run unsubstantiated claims against the church, adding that the advertisement contained information gleaned from public sources.

Officials with the Mormon Church had no comment on Tuesday.

"I was furious that a company the size of Comcast would pull this minuscule ad buy and deny our organization its First Amendment rights," Karger said, noting that he believed that the cable giant "caved" in to pressure from the politically powerful church. To register his displeasure and appeal to a higher corporate power, Karger has sent a letter of protest to Comcast CEO Brian Roberts in Philadelphia.

Karger said that he found the explanation on why Comcast blocked the advertisements arbitrary and ridiculous: If Comcast won't air demeaning commercials, how could it televise Donald Trump and Hillary Clinton attack ads during the presidential campaign?

Comcast spokeswoman Hunter said there are different requirements for political advertisements.