Same-sex marriage has officially been legalised in Northern Ireland

The first marriages are expected to take place in the week of Valentine's Day.

Rainbow Project director John O'Doherty and his partner on stage during a same-sex marriage march in Belfast. Source: AAP

Same-sex couples will now be able to get married in Northern Ireland, more than six years after it was legalised throughout the rest of the United Kingdom.

Northern Ireland's parliament, the Stormont, did not follow England, Wales and Scotland in introducing legislation to allow same-sex marriage in 2013, due to a lack of cross-party support.

A mural in support of same sex marriage in Belfast. Source: AAP

The Stormont requires parties from both the republicans and unionists to share leadership, but this agreement fell apart in 2017 when nationalist party Sinn Fein withdrew, saying it was not being treated equally by the Democratic Unionist Party.

Until recently, the three-year standoff meant Northern Ireland effectively had no government.

In July last year, the British Parliament passed legislation to bring the province into line with the rest of the UK, dictating that regulations governing same-sex marriage and civil partnerships will be made no later than 13 January, unless the devolved government was restored before 21 October.

Northern Ireland's neighbour, the Republic of Ireland, was the first country to put same-sex marriage to a public vote in 2015, with 62 per cent of the public voting yes in the referendum.

Because people must submit an intention to marry 28 days before the ceremony, first marriages in Northern Ireland are expected to take place in the week of Valentine's Day.

Couples that have already married outside Northern Ireland will be recognised as such immediately. 

With Reuters.