Ivan Cooper, a veteran of the civil rights movement in Northern Ireland, has died at the age of 75.
It has been reported by several media sources that Mr. Cooper passed away in hospital on Wednesday morning.
S.D.L.P. leader, Colum Eastwood, led the tributes to Mr. Cooper who was one of the party's founding members.
“Ivan Cooper was born to break the mould," said Mr. Eastwood.
"A working class Protestant man who saw a common injustice and inequality that had taken root in Protestant and Catholic communities, he dedicated his life to fighting it.
“As an early leader in the Civil Rights Movement, few have contributed as much to peace and equality on this island than Ivan.
"Organising marches in Derry for the right to a home, the right to a job and the right to a vote, Ivan often put himself in the path of danger to secure justice for people in every community.
"And on many occasions that meant that he suffered vilification and violence for his convictions.
"It never stopped him.
"Alongside his close friend John Hume, he helped blaze the trail on the path that led to the Good Friday Agreement."
Mr. Eastwood went on to say his thoughts and prayers were with Mr. Cooper's family.
“Anyone who knew Ivan knows that his selfless passion for justice continued to burn brightly into his later years.
"His unwavering belief that people on this island should come together to fight for common ideals and in their common interest is a lesson for us all.
"Especially as we face political division today."
Mr. Eastwood added: “A man of sharp contrasts, sharp intellect and, it must be said, sharp tongue, he stands as a giant in the story of this island.
"And he holds a special place in the hearts of S.D.L.P. members.
“I want to express my deepest sympathies to Ivan’s wife Francis, his daughters Sinead and Bronagh and his entire family circle at this difficult time."