A television ad suggesting there’s more to same sex marriage than has been considered so far in public debates has been denied airings on Channel 10, Channel 7 and some radio stations this week.

The ad campaign, titled “There’s more to it than you think,” was created by newly formed group the Marriage Alliance and launched this week in Sydney. The ads depict same-sex marriage arguments around equality as just the “tip of the iceberg” of issues that haven’t yet had a proper public airing.

The ad lists issues such as “how [same sex marriage] will affect children or sex education in schools or even what rights you could lose” as some of the “important issues” that “are taking a back seat” in the current same-sex marriage debates. Watch the 15 second TVC below:

The Marriage Alliance called the decision by Channel 7 and 10 a “black-ban”, while the Australian Christian Lobby was quick to comment on the decision, suggesting that political viewpoints were being “censored”.

“This is a chilling display of the dangerous tendency to censor debate on marriage,” said ACL’s managing director Lyle Shelton.

The advertising campaign was seeking advertising spots “over the next few weeks,” according to the Marriage Alliance, in the lead up to an expected vote on same-sex marriage in the next federal parliamentary sitting that starts on Monday. Marriage Alliance has received confirmation from Channel 9 and Foxtel that the ad will air from this week on those stations.

Eternity asked Channel 7’s director of corporate affairs, Simon Francis, why the decision was made not to run the Marriage Alliance ads. In an email, Mr Francis said, “We could not accommodate the booking request.”

Daily Telegraph columnist Piers Akerman today heard a similar story from Channel 7. “A Seven spokesman said there was no politics in the decision and the station didn’t have a 15-second spot.”

The Marriage Alliance website features a countdown for when politicians will “return [to Canberra] to vote on same-sex marriage”. A multi-party marriage equality bill is expected to be moved in Parliament during the next sitting. At time of writing, the Marriage Alliance countdown was two days, 18 hours, 52 minutes.

So, could the Marriage Alliance have just asked for the ads too late?

Marriage Alliance spokesperson Sophie York doesn’t think so. Another Marriage Alliance spokesperson told Eternity they had booked ads on Channel 7 and 10 and had them “locked in” two weeks ago. But last week both channels responded by saying the bookings could not be made, though Marriage Alliance received nothing in writing.

“We can only then deduce that we’re being subject to a ban, a last-minute refusal. We can only go on what’s presented to us … they accepted the booking and there’s been no grounds provided for why they can’t run them,” said Ms York. “It doesn’t add up.”

“It is quite shocking that two major TV networks are denying the basic right to freedom of speech and expression on an issue that supports the current law of the nation,” Ms York said.

In March, a television ad from the Australian Marriage Forum intended to be screened during the Sydney Gay and Lesbian Mardi Gras was pulled by SBS. It urged Australians to “think of the child” when considering same-sex marriage. While SBS did not allow the ad, saying it reserved the right to determine what adverts it broadcasts, the ad was aired on Channel 7 and Channel 9.

Ms York said that the climate must have changed for Channel 7. “It shows that something’s changed at 7. Channel 9 are clearly still open to all comers, and happy to have different view points put forward.”

Australian Marriage Equality, the campaign group that supports same sex-marriage, has a fundraising campaign open to create TV ads to “ensure MPs and senators who have not yet declared this position [on same-sex marriage] see it.” Whether Channel 7 and 10 will air those ads remains to be seen.

The Marriage Alliance was founded by Tio Faulkner, a member of the ACT Liberal Party. Its founding directors include former investment banker Jim Dominguez, Queensland businessman Ashley Goldsworthy and business adviser Mark Phillips, who all have Catholic affiliations.

Mr Dominguez was invested with the Papal honours as Knight Commander of the Order of St Gregory the Great for his contribution to education and health. He was chairman of a campaign against euthanasia in the 1990s. Mr Goldsworthy is currently on the Brisbane Catholic Education Council and Mr Phillips was a member of review panel in the Catholic Education Office in Sydney in 2014.

Longer versions of the Marriage Alliance ads can be viewed here.