Addressing the launch event, SIPTU Campaigns and Equality Organiser, Ethel Buckley, said: “This is a significant event for the Irish trade union movement and it's fitting that it should take place here in Liberty Hall, Halla na Saoirse. This is indeed a hall of liberty associated with the historic struggle of Irish workers for over a century.

“Tonight the Irish trade union movement raises the Rainbow flag in solidarity as we launch the campaign for civil marriage equality.”

She added: “We recognise that some voters, including trade union members, will have questions about the referendum and we will endeavour to answer those questions and to address fears played upon by those who have consistently opposed social change in Ireland.”

Congress President, John Douglas, said: “Congress is calling for a ‘Yes’ vote. We believe that civil marriage should be available to all who seek it. There can be no such thing as a two tier system of equality and LGBT citizens deserve full and equal treatment.”

Among the over 200 people who attended the event where NUJ Ireland Secretary, Seamus Dooley and Minister of State at the Department of Justice and Equality, Aodhán Ó Ríordáin.

The Minister cautioned against those who will seek to use fear of change to defeat the referendum.

He said: “What the No side have as their great benefit is fear. And when you are involved in a referendum campaign you always have to ask people to make a leap of faith to vote ‘Yes’ because you are asking people to make a change.”

During the launch the roof of Liberty Hall was illuminated in rainbow colours.