The first openly gay state MP, Ian Hunter, will marry his long-term partner, Leith Semmens, in Spain at the end of the year.

It is believed Mr Hunter will be the first sitting gay politician of any Australian parliament to be married, although the ACT's Andrew Barr has entered a civil union with his partner, The Advertiser reported.

Mr Hunter and Mr Semmens, who have been together for more than 20 years, had planned to marry in New York last year but were held up because the Federal Government refused to grant the necessary paperwork that would have allowed the ceremony to be conducted in the US.

"We have had a long-term plan to go to Spain ... so we decided to get married there," Mr Hunter said in an interview for today's saweekend magazine, which tells the story of his long climb to a position in Cabinet.

He said it would be a "very traditional" ceremony. Mr Hunter was elected to Parliament in 2006 and promoted to Cabinet last October by Premier Jay Weatherill. His portfolios include social inclusion, disabilities, social housing and communities.

Spain changed its legislation to allow gay marriage in 2005 and more than 20,000 ceremonies have been held since then.

However, the marriage will not be recognised under Australian law.

But the national convenor of lobby group Australian Marriage Equality, Alex Greenwich, said the marriage of Mr Hunter and Mr Semmens would send a positive message that the law should be changed. "Things like that have a huge impact," he said yesterday.

"This is a marriage that will be recognised in something like 20 countries but not in Australia where he is a ... respected politician."

A Bill to recognise same-sex marriages is likely to be introduced in Parliament this year.

In December, the ALP altered its platform to support same-sex marriage but agreed to allow MPs a conscience vote instead of being bound by the policy to appease Prime Minister Julia Gillard, who opposes reform.

Source: News.com.au