Australia is one of the few developed nations which has yet to legalise same-sex marriage despite a Newspoll survey on Monday showing it is supported by 63 percent of Australians.

Australians will be asked their views on same-sex marriage in a non-compulsory non-binding ballot due to begin next month. If the population votes in favour of gay marriage, then a vote in parliament is expected later in the year.

Here are the facts about same-sex marriage around the world:

Same-sex marriage is legal in 24 countries: Argentina, Belgium, Brazil, Britain, Canada, Colombia, Denmark, Finland, France, Germany, Iceland, Ireland, Luxembourg, Malta, Mexico, Netherlands, New Zealand, Norway, Portugal, South Africa, Spain, Sweden, Uruguay, United States.
In some of these countries, such as Mexico and Britain, marriage is only open to same-sex couples in some regions. Northern Ireland is the only part of the United Kingdom where same-sex marriage is not allowed.
Almost one in three adults globally believe people of the same sex should be allowed to marry, a survey of almost 100,000 people in 65 countries showed in 2016.