Despite the prospect of defeat meeting their initiatives, two Australian lawmakers introduced separate bills on Monday supporting the federal legislation of gay union in the country.

At present, same-sex marriage is recognised by only five Australian states, with the federal government already clear on its position against the proposal.

Prime Minister Julia Gillard has already declared that she will not support any form of the legislation while the conservative Liberal-National Coalition has reiterated its position that marriage is only reserved between a man and woman.

"We believe that a marriage is between a man and a woman and that's the way the Coalition will be voting," Liberal leader Joe Hockey told Agence France Presse (AFP) on Monday.

Hockey echoed the long-standing position of Opposition Leader Tony Abbott, who had earlier indicated that the Coalition will oppose any moves to alter the normal marriage set-up in Australia.

Abbott also stressed that he expected member of the Coalition to vote within the party line, with threats of punishments for those veering away from the Liberal stance.

Notwithstanding, Australian Green MP Adam Bandt and Labor MP Stephen Jones filed their private member bills in hopes of at least attracting a serious review by the Australian Senate.

The Senate is already reviewing the earlier gay marriage proposal lodged earlier in September 2010 by Greens Senator Sarah Hanson-Young and Australian Marriage Equality (AME) is asking the senators to look into the three versions and perhaps develop them into something more acceptable for everyone.

AME convenor Alex Greenwich characterised the bills filed by Bandt and Jones as paving the road to equality.

While he conceded that the bills will not flourish in the Parliament, they will at least signal the gathering of support for gay marriages following the federal government's declaration on December last year that withdrew its initial support for the proposal.

"Three months ago the Labor Party was officially opposed to reform and now we have a Labor member leading the way towards equality," Greenwich told AFP.

"The Jones bill demonstrates the immense momentum behind reform," he added.

Ms Gillard has successfully steered the Labor party away from supporting the same-sex union proposal late last year amidst fierce opposition from factions within the ALP or MPs supporting her minority rule.

She, however, allowed Labor MPs to vote on the measures basing on their conscience but gay union proponents lamented that the Prime Minister's position fell of short of giving the proposal a significant legal boost.