Peter Garret, the former Midnight Oil front man and recently promoted Federal Shadow Minister for Heritage, the Environment and the Arts, has broken with his party's line on national television by announcing he is a supporter of gay marriage.

This is the first time a senior Labor politician has backed same-sex marriage, with the ALP having so far even refused to commit to civil unions, and the party is officially still yet to back away from the bipartisan support it gave to the Federal Government's same-sex marriage ban in 2004 when Mark Latham was still the Opposition leader.

He made the declaration during an appearance on Channel 10's late night variety show "The Big Night In With John Foreman" in a pre-recorded episode aired on Thursday the 21st of December.

The episode was recorded at the start of December before Garrrett's promotion but was not broadcast until now.

During the interview, Garrett, a committed Christian referred to himself as a "social conservative" in favour of "the family", and explained the reasons behind his recent vote against therapeutic cloning in the Federal Parliament.

However, when asked by host John Foreman if this conservatism extended to the issue of gay marriage, Garrett said, "I don't have a problem with it".

Garrett went on further to say that the spectrum of diversity in society needed to be respected and that Governments had no place legislating sexual morality.

He also called the Bush Administration's legislative campaign against same-sex marriage a "divisive" tactic but did not comment on his own party's support for similar initiatives here.

However, when asked in general what the Labor recruit would do if his party was to push for policies he disagreed with, Garrett indicated he was prepared to vote with the ALP consensus on such issues, but in such cases would continue to lobby for the approaches he thought right within the party room.