Tasmania's Labor Premier, Lara Giddings, announced at the weekend that her government would introduce a bill to introduce same-sex marriage on the island state.

Deputy Chief Minister Andrew Barr and Attorney-General Simon Corbell indicated yesterday that the ACT government would consider following suit if Ms Giddings' bill was approved by the Tasmanian Parliament and survived a High Court challenge.

But their preference was for the Federal Parliament to amend the Marriage Act to recognise same-sex unions throughout Australia.

Mr Barr said permitting same-sex couples from interstate to be married in Canberra could create significant economic opportunities for the ACT.

He said the ACT government would push ahead with a proposed change to the local civil unions regime that would allow same-sex couples to have legally binding civil union ceremonies.

''I think we should also examine what happens in Tasmania and be open to looking at a similar change to the law,'' Mr Barr said. ''If that were the case then I would certainly be advocating for the law to allow non-ACT residents to come to the ACT.

''I think the Tasmanian Premier has a legitimate point in relation to the economic opportunities there.

''That's certainly something I would pursue within the government as minister for Economic Development and Minister for Tourism.''

A report issued earlier this year estimated that becoming Australia's first gay marriage destination could be worth $100 million to the Tasmanian economy.

Mr Barr said he and his long-term partner Anthony Toms would not consider getting married in Tasmania as they want to ''get married here in our own community''.

The Federal Parliament has the power to quash ACT laws.

But Mr Barr believed it was less likely an ACT gay marriage law would be overturned if one was already successfully operating in Tasmania.

Mr Corbell said he hoped the Tasmanian gay marriage proposal would boost the chances of the Civil Unions bill passing the ACT Legislative Assembly this month.

''At this time our commitment is to the passage of the civil unions bill and this really … strengthens our argument that the bill should be passed,'' Mr Corbell said.

The bill was closely modelled on a law that was overturned by the Howard government in 2006.

A spokeswoman for the ACT Opposition said the Canberra Liberals would not support gay marriage.

''The Canberra Liberals' position on same-sex marriage hasn't changed,'' the spokeswoman said.

ACT Greens legal affairs spokesman Shane Rattenbury said his party's preference was for a change to the Commonwealth Marriage Act to allow same-sex marriage but it had considered introducing its own bill into the ACT Assembly.

''We've been thinking about doing it … but we were waiting to see how the national debate went,'' Mr Rattenbury said.

Prime Minister Julia Gillard is personally opposed to same-sex marriage and yesterday refused to say whether she would consider launching a legal challenge to a Tasmanian same-sex marriage law.

Federal Labor MPs will have a conscience vote when a private members bill on same-sex marriage is debated.