Conservative Liberal senator Eric Abetz has slammed the country's top business leaders over a fresh push on same-sex marriage, saying Australians were "fed up" with political correctness being placed above services.

Companies including Qantas, ANZ, Google and eBay on Monday launched a new campaign on marriage equality, in stark defiance of Immigration Minister Peter Dutton's advice to "stick to their knitting".

The initiative invites customers to order one of 250,000 specially-commissioned rings bearing the phrase "until we all belong" - which will also appear on Qantas boarding passes and other paraphernalia.

The ring is incomplete, representing the "gap" in equality between same-sex couples and their heterosexual peers. In a series of video advertisements, straight allies are encouraged to wear the rings "until we all belong".