One of the Turnbull government's most senior ministers has launched a venomous assault on the bosses of Telstra and other large companies for engaging in "fringe" issues like gay marriage.

Cabinet minister Peter Dutton urged company chief executives to stop shoving "your politically correct views down our throats" and instead focus on running their businesses.

The extraordinary spray came after 20 heads of some of the country's largest companies penned a letter to Malcolm Turnbull, urging him to legislate for same-sex marriage.

Mr Dutton labelled their lobbying effort "bizarre" and "an outrage".

"The CEOs would be better off out there arguing at the moment for the economy to be run a particular way or for tax to be reformed in this way so that they can grow their businesses and grow jobs, as opposed to taking on these moral causes," he told Ray Hadley on 2GB radio on Thursday.

"If they want to run for politics, well, you know, resign from their position, stick their hand up at the next election, but don't jam your politically correct views down our throats."

Mr Dutton took aim at Telstra, saying it would be better off cleaning up call centre operations than wading into political debate.

"Once all that's done, you've then got time on your hands to concentrate on these other fringe issues," he said.

Marriage equality campaigner Ivan Hinton-Teoh said the minister was simply trying to shut down views he disagreed with.

"All Australians should be free to voice their views and lobby politicians, including those business leaders who support marriage equality," he said.

"Many CEOs recognise the importance of equality for their employees and customers, and have a right to represent that to lawmakers."

But Mr Dutton insisted the CEOs ought to leave debate on social issues to politicians, talkback hosts and "normal" people.

"I just think it's high time these people pulled back from these moralistic stances and we'd be a better society without them," he said.

Prime Minister Malcolm Turnbull was unswayed by the letter from the chief executives.

"Our policy on this is well-known, which we took to the election. There should be a plebiscite on the issue first," he told reporters in regional NSW on Thursday.

"The Labor Party has frustrated that by opposing it in the Senate, despite the fact that Mr Shorten only three years ago gave his very public and vocal support for a plebiscite which would give every Australians a say on the matter."