Sir Elton John feels ''huge guilt and regret'' over his first marriage.

The 'Candle in the Wind' singer tied the knot with German sound engineer Renate Blauel in Sydney, Australia, in 1984, but he admits the fact he had ''denied who [he] really was'' by going through with the ceremony caused so much ''sadness'' to a ''wonderful woman''.

Elton - who came out as bisexual in 1976 but clarified he was gay in 1988 after divorcing Renate - said: ''Many years ago, I chose Australia for my wedding to a wonderful woman for whom I have so much love and admiration. I wanted more than anything to be a good husband, but I denied who I really was, which caused my wife sadness, and caused me huge guilt and regret.

''To be worthy of someone's love, you have to be brave enough and clear eyed enough to be honest with yourself and your partner.''

The 70-year-old singer has spoken out to back marriage equality in Australia ahead of his tour Down Under and spoke of how proud he is that he and long-term partner David Furnish - who he wed in December 2014, nine years after their civil partnership ceremony - have been able to marry and have their relationship ''accepted by the world''.

In a post on Instagram, he continued: ''Almost 24 years ago, I met the person with whom I could be fully myself.

''When we married in 2014, it felt like that fact was accepted by the world.

''For David and I, being able to openly love and commit to one another, and for that to be recognised and celebrated is what makes life truly worth living.

''That acceptance and support makes us want to be as kind, responsible and productive members of society, as well as the best parents, that we can be.''

And the 'Rocket Man' hitmaker - who has sons Zachary, six, and Elijah, with David - went on to urge Australia to legalise same-sex marriage.

He concluded: ''I love Australia. I love its spirit, it's lack of pretence, it's passion. I hope it can embrace the honesty and courage that seeks gay marriage as an expression not of desire but of love. #loveislove #marriageequality (sic)''