Picture - Kevin Scott / Presseye Saturday 13th June 2015 - Amnesty International March for Equality Pictured is the Amnesty International March for Equality as it makes its way through Belfast City Centre. Picture - Kevin Scott / Presseye

Pacemaker press 13/6/15 Pictured are long term civil partners Cathrine Couvert and Sally Bridge.Thousands of people have attended a march in Belfast, calling for the introduction of civil marriage for same-sex couples in Northern Ireland. The march began at Writer's Square and moved towards Belfast City Hall, where a rally was held.The organisers said Northern Ireland is "out on a limb" as the only part of the UK and Ireland not to change its laws. The Northern Ireland Assembly has debated the issue four times, and each time MLAs rejected same-sex marriage. Picture Mark marlow/pacemaker press

Pacemaker press 13/6/15 Thousands of people have attended a march in Belfast, calling for the introduction of civil marriage for same-sex couples in Northern Ireland. The march began at Writer's Square and moved towards Belfast City Hall, where a rally was held.The organisers said Northern Ireland is "out on a limb" as the only part of the UK and Ireland not to change its laws. The Northern Ireland Assembly has debated the issue four times, and each time MLAs rejected same-sex marriage. Picture Mark marlow/pacemaker press

Pacemaker press 13/6/15 Pictured is John Doherty of the Rainbow project. Thousands of people have attended a march in Belfast, calling for the introduction of civil marriage for same-sex couples in Northern Ireland. The march began at Writer's Square and moved towards Belfast City Hall, where a rally was held.The organisers said Northern Ireland is "out on a limb" as the only part of the UK and Ireland not to change its laws. The Northern Ireland Assembly has debated the issue four times, and each time MLAs rejected same-sex marriage. Picture Mark marlow/pacemaker press

Pacemaker press 13/6/15 Pictured are Ellie McEaveney and Meabh Neeson giving their support to Gay marriage as thousands of people have attended a march in Belfast, calling for the introduction of civil marriage for same-sex couples in Northern Ireland. The march began at Writer's Square and moved towards Belfast City Hall, where a rally was held.The organisers said Northern Ireland is "out on a limb" as the only part of the UK and Ireland not to change its laws. The Northern Ireland Assembly has debated the issue four times, and each time MLAs rejected same-sex marriage. Picture Mark marlow/pacemaker press

Pacemaker press 13/6/15 Pictured are Ellie McEaveney and Meabh Neeson giving their support to Gay marriage as thousands of people have attended a march in Belfast, calling for the introduction of civil marriage for same-sex couples in Northern Ireland. The march began at Writer's Square and moved towards Belfast City Hall, where a rally was held.The organisers said Northern Ireland is "out on a limb" as the only part of the UK and Ireland not to change its laws. The Northern Ireland Assembly has debated the issue four times, and each time MLAs rejected same-sex marriage. Picture Mark marlow/pacemaker press

Pacemaker press 13/6/15 Pictured giving her support to Gay marriage is Aibhrean Black as thousands of people have attended a march in Belfast, calling for the introduction of civil marriage for same-sex couples in Northern Ireland. The march began at Writer's Square and moved towards Belfast City Hall, where a rally was held.The organisers said Northern Ireland is "out on a limb" as the only part of the UK and Ireland not to change its laws. The Northern Ireland Assembly has debated the issue four times, and each time MLAs rejected same-sex marriage. Picture Mark marlow/pacemaker press

Pacemaker press 13/6/15 Thousands of people have attended a march in Belfast, calling for the introduction of civil marriage for same-sex couples in Northern Ireland. The march began at Writer's Square and moved towards Belfast City Hall, where a rally was held.The organisers said Northern Ireland is "out on a limb" as the only part of the UK and Ireland not to change its laws. The Northern Ireland Assembly has debated the issue four times, and each time MLAs rejected same-sex marriage. Picture Mark marlow/pacemaker press

Pacemaker press 13/6/15 Thousands of people have attended a march in Belfast, calling for the introduction of civil marriage for same-sex couples in Northern Ireland. The march began at Writer's Square and moved towards Belfast City Hall, where a rally was held.The organisers said Northern Ireland is "out on a limb" as the only part of the UK and Ireland not to change its laws. The Northern Ireland Assembly has debated the issue four times, and each time MLAs rejected same-sex marriage. Picture Mark marlow/pacemaker press

Pacemaker press 13/6/15 Thousands of people have attended a march in Belfast, calling for the introduction of civil marriage for same-sex couples in Northern Ireland. The march began at Writer's Square and moved towards Belfast City Hall, where a rally was held.The organisers said Northern Ireland is "out on a limb" as the only part of the UK and Ireland not to change its laws. The Northern Ireland Assembly has debated the issue four times, and each time MLAs rejected same-sex marriage. Picture Mark marlow/pacemaker press

Picture - Kevin Scott / Presseye Saturday 13th June 2015 - Amnesty International March for Equality Pictured is the Amnesty International March for Equality as it makes its way through Belfast City Centre. Picture - Kevin Scott / Presseye

Picture - Kevin Scott / Presseye Saturday 13th June 2015 - Amnesty International March for Equality Pictured is the Amnesty International March for Equality as it makes its way through Belfast City Centre. Picture - Kevin Scott / Presseye

Picture - Kevin Scott / Presseye Saturday 13th June 2015 - Amnesty International March for Equality Pictured is the Amnesty International March for Equality as it makes its way through Belfast City Centre. Picture - Kevin Scott / Presseye

Picture - Kevin Scott / Presseye Saturday 13th June 2015 - Amnesty International March for Equality Pictured is the Amnesty International March for Equality as it makes its way through Belfast City Centre. Picture - Kevin Scott / Presseye

Picture - Kevin Scott / Presseye Saturday 13th June 2015 - Amnesty International March for Equality Pictured is the Amnesty International March for Equality as it makes its way through Belfast City Centre. Picture - Kevin Scott / Presseye

Picture - Kevin Scott / Presseye Saturday 13th June 2015 - Amnesty International March for Equality Pictured is the Amnesty International March for Equality as it makes its way through Belfast City Centre. Picture - Kevin Scott / Presseye

Picture - Kevin Scott / Presseye Saturday 13th June 2015 - Amnesty International March for Equality Pictured is the Amnesty International March for Equality as it makes its way through Belfast City Centre. Picture - Kevin Scott / Presseye

Picture - Kevin Scott / Presseye Saturday 13th June 2015 - Amnesty International March for Equality Pictured is the Amnesty International March for Equality as it makes its way through Belfast City Centre. Picture - Kevin Scott / Presseye

Picture - Kevin Scott / Presseye Saturday 13th June 2015 - Amnesty International March for Equality Pictured is the Amnesty International March for Equality as it makes its way through Belfast City Centre. Picture - Kevin Scott / Presseye

Pacemaker press 13/6/15 Pictured is Canon Charles Kenny. Thousands of people have attended a march in Belfast, calling for the introduction of civil marriage for same-sex couples in Northern Ireland. The march began at Writer's Square and moved towards Belfast City Hall, where a rally was held.The organisers said Northern Ireland is "out on a limb" as the only part of the UK and Ireland not to change its laws. The Northern Ireland Assembly has debated the issue four times, and each time MLAs rejected same-sex marriage. Picture Mark marlow/pacemaker press

Pacemaker press 13/6/15 Pictured are long term civil partners Cathrine Couvert and Sally Bridge.Thousands of people have attended a march in Belfast, calling for the introduction of civil marriage for same-sex couples in Northern Ireland. The march began at Writer's Square and moved towards Belfast City Hall, where a rally was held.The organisers said Northern Ireland is "out on a limb" as the only part of the UK and Ireland not to change its laws. The Northern Ireland Assembly has debated the issue four times, and each time MLAs rejected same-sex marriage. Picture Mark marlow/pacemaker press

Picture - Kevin Scott / Presseye Saturday 13th June 2015 - Amnesty International March for Equality Pictured is the Amnesty International March for Equality as it makes its way through Belfast City Centre. Picture - Kevin Scott / Presseye

Picture - Kevin Scott / Presseye Saturday 13th June 2015 - Amnesty International March for Equality Pictured is the Amnesty International March for Equality as it makes its way through Belfast City Centre. Picture - Kevin Scott / Presseye

Picture - Kevin Scott / Presseye Saturday 13th June 2015 - Amnesty International March for Equality Pictured is the Amnesty International March for Equality as it makes its way through Belfast City Centre. Picture - Kevin Scott / Presseye

Pacemaker press 13/6/15 Pictured are Ellie McEaveney and Meabh Neeson giving their support to Gay marriage as thousands of people have attended a march in Belfast, calling for the introduction of civil marriage for same-sex couples in Northern Ireland. The march began at Writer's Square and moved towards Belfast City Hall, where a rally was held.The organisers said Northern Ireland is "out on a limb" as the only part of the UK and Ireland not to change its laws. The Northern Ireland Assembly has debated the issue four times, and each time MLAs rejected same-sex marriage. Picture Mark marlow/pacemaker press

Picture - Kevin Scott / Presseye Saturday 13th June 2015 - Amnesty International March for Equality Pictured is the Amnesty International March for Equality as it makes its way through Belfast City Centre. Picture - Kevin Scott / Presseye

Pacemaker press 13/6/15 Thousands of people have attended a march in Belfast, calling for the introduction of civil marriage for same-sex couples in Northern Ireland. The march began at Writer's Square and moved towards Belfast City Hall, where a rally was held.The organisers said Northern Ireland is "out on a limb" as the only part of the UK and Ireland not to change its laws. The Northern Ireland Assembly has debated the issue four times, and each time MLAs rejected same-sex marriage. Picture Mark marlow/pacemaker press

Picture - Kevin Scott / Presseye Saturday 13th June 2015 - Amnesty International March for Equality Pictured is the Amnesty International March for Equality as it makes its way through Belfast City Centre. Picture - Kevin Scott / Presseye

20,000 people have turned out in Belfast city centre to call for the legalisation of same-sex marriage in Northern Ireland, according to Amnesty International.

The march, organised by Amnesty, the Irish Congress of Trade Unions and the Rainbow Project, began at the Ulster University at York Street at 2.30pm and ended with speeches outside City Hall.

The Northern Ireland campaign for the introduction of same-sex marriage has been buoyed by the success of the recent referendum in the Republic - and by a wave of celebrity endorsements from the world of sport, music and theatre.

The province is now set to be the only part of the UK or Ireland where civil marriage is denied to gay couples.

Unionists have rejected four Sinn Fein motions calling on the Executive to legislate for marriage equality.

Celebrity supporters of the campaign include Olympic boxer Paddy Barnes, singers Brian Kennedy, Gary Lightbody and Bronagh Gallagher and actress Nuala McKeever.

Belfast Telegraph