The Catholic church lobbied two of Australia's most prominent gay chief executives to stop their companies' support for marriage equality.

Fairfax Media understands the Catholic Archdiocese of Sydney contacted Qantas chief executive Alan Joyce and SBS chief executive Michael Ebeid, urging them to reconsider their public endorsement of same-sex marriage.

Both companies were among hundreds of Australian corporations to pledge their support for the Australian Marriage Equality campaign last year, and both chief executives addressed a high-profile breakfast hosted by the AME in May.

Shortly after the AME campaign was launched, the Catholic church addressed letters to many of the organisations involved, including Qantas, SBS, Telstra, the Football Federation of Australia and law firm Maurice Blackburn.

"I wonder whether you have questioned whether it is the role of a corporation such as yours to be participating in such an important matter that impacts all of Australian society now and into the future," wrote Sydney archdiocese business manager Michael Digges. The form letters were sent to many organisations and did not mention the sexuality of the companies' chief executives.

This week it was revealed by The Australian that Telstra had backed away from its public support for marriage equality, in a decision that followed lobbying by the Catholic church's Sydney archdiocese, including a meeting between former chairwoman Catherine Livingstone and Sydney Archbishop Anthony Fisher.

Telstra did not explicitly deny the church played a role in their decision. In a statement, chief executive Andrew Penn said the company had pulled back to allow clear air ahead of a proposed plebiscite on the issue. It prompted numerous customers to vow they would cancel their contracts with the telco.

Mr Joyce and Mr Ebeid told an AME breakfast last May that marriage equality was an important issue for corporate Australia - because it would help retain or attract gay and lesbian talent to Australia, and could even boost productivity by reducing people's prejudice. "That's why marriage equality is very important for corporations, so that people don't feel that they are a second-class citizen," Mr Ebeid said.

Mr Joyce met his partner Shane Lloyd 15 years ago in Melbourne. In the past year, the boss of Australia's national carrier has assumed a more public role in the debate about marriage equality. "It's really about equality," he told Fairfax Media last year, and observed "how important it is for a business leader ... to express our views on things".

Following a successful referendum on same-sex marriage in his birth country of Ireland, Mr Joyce was profiled by LGBTI magazine Star Observer. At that point, almost 600 Australian companies had pledged their support for marriage equality, including Qantas, Virgin and the major banks. "If you're unhappy with a company that's involved with the campaign you won't be able to bank and you won't be able to fly anywhere," Mr Joyce said.

Fairfax Media contacted several leading corporations that have signed their support for marriage equality, including Telstra's rivals, who said they would not let external lobbying change their activities.

Virgin Mobile chief executive David Scribner said the company had not been contacted by the Catholic church but "regardless, pressure from these sorts of organisations would not affect our position on equality issues".

A spokeswoman for Vodafone said they were contacted by "a range of organisations" from time to time, but would not specify. "When we receive enquiries in relation to marriage equality, we respond with confirmation of our steadfast support and reasons for it," she said.

Other signatories, including Kmart, QBE and HSBC, said they had not been contacted by the Catholic church.

Fairfax Media approached the Catholic communications office for comment.

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