Several major international companies operating in Northern Ireland have called for same-sex marriage to be introduced.

Northern Ireland is the only part of the UK or Ireland to outlaw same-sex marriage.

Business leaders from sectors including finance have called for change and said an inclusive workforce, free to express itself was more productive and would help attract the best talent from across the world.

Leigh Meyer, managing director of the Citi financial services firm in Belfast, said: "We make a stand with the LGBT community and apply pressure on the legislative bodies to make marriage equality a reality.

"It is not just the right thing to do, it is the only thing to do, it is the proper thing to do."

A vocal campaign has called for the introduction of same-sex marriage in Northern Ireland. Credit: PA

Consultants Deloitte and PwC, Bank of Ireland, Ulster Bank, soft drinks manufacturer Coca Cola Ireland and law firm Pinsent Masons were among those who signed a letter calling for the landmark reform.

The joint letter from businesses said: "As employers we encourage and welcome diversity and inclusion in our workforce and recognise the rights of our lesbian, gay, bisexual and/or transgender employees to be themselves and to live and work free from discrimination, prejudice or exclusion."

Meyer added: "We all seek for Northern Ireland to be inclusive, equitable and fair, a progressive society that includes all of its citizens and residents in access to basic rights and opportunities."

Northern Ireland's biggest political party, the Democratic Unionists, oppose change on religious grounds, arguing civil partnerships are available to same-sex couples but marriage is between a man and a woman.

John O’Doherty said the impact of the drive had been 'awesome' already. Credit: PA

John O’Doherty, director of the Rainbow Project which advocates for same-sex marriage, said it represented leadership from a sector which could not be ignored.

He said their impact had already been "awesome", including supporting LGBT employees/colleagues to bring their whole selves to work and revising policies aimed at promoting diversity and inclusion.

"They can hold their heads high and know that they are respected and supported and valued by their employers."

O'Doherty said in order to achieve a prosperous future for Northern Ireland, "We believe our people should have equal access to the same rights, entitlements, responsibilities and freedoms enjoyed elsewhere in the United Kingdom."

DUP leader Arlene Foster has attended a PinkNews event at Stormont at the invitation of Citi.