An Irish priest who spent much of his life championing the rights of those with HIV in Africa was a "true hero", the president has said.

Father Michael Kelly, who spent more than 50 years in Zambia as a missionary and educator, died on Friday.

He worked tirelessly to educate and promote safe behaviour among youth and those most at risk from HIV throughout sub-Saharan Africa and much further afield, his website said.

😢 to hear of passing of this giant of a man. Prof Fr Michael Kelly died in his beloved Zambia.

What a life. Educator. Activist. Champion of the rights of people with HIV when it was still an early scary phenomenon. Always proud of Irish roots but Always in love with Africa. pic.twitter.com/9JFoaSRIZo

— Kevin Kelly (@kevinthehague) January 15, 2021

Michael D Higgins said: "I offer my condolences to his family and many friends. Ireland and Zambia mourn the loss of a true hero."

He praised Father Michael for his intellect, his extraordinary positivity and his compassion.

Mr Higgins said: "He epitomised the great work of Irish missionaries in the education and health spheres in so many parts of the world.

"His humanity shone through in his work and in his encounters with all who were fortunate enough to have met him."

Foreign Affairs Minister Simon Coveney said Father Michael's leadership and advocacy on HIV and Aids, and also education and human rights, was inspirational.

Minister @simoncoveney has expressed his condolences to the family of Fr. Michael Kelly, following his death today in Zambia.

Fr. Kelly leaves a legacy of achievement and his energy, dedication & passion will live on in the memories of those he inspired: https://t.co/s6hHo2Jdsn. pic.twitter.com/13Xv4dbQlx

— Irish Foreign Ministry (@dfatirl) January 15, 2021

He said: "He leaves a legacy of achievement, driving policy changes not just in Zambia but on the international stage.

"It was fitting that his outstanding work was marked during his lifetime, including awards for distinguished service from President Higgins in 2012, and President Lungu of Zambia in 2018.

"Fr. Michael made an immense contribution to improved health outcomes for many people in Sub-Saharan Africa."

Statement from President Higgins on the death of Father Michael Kelly:https://t.co/wIN7vjVLg7

— President of Ireland (@PresidentIRL) January 15, 2021

"Father Michael's energy, dedication, and passion will live on in the memories of those he inspired."

Father Michael was a former headmaster at a school in Zambia, took his PhD and became a pro-vice chancellor at the University of Zambia.

Since 2006, Irish Aid has honoured his achievements through the annual Father Michael Kelly HIV/Aids event, often timed to coincide with World Aids Day in December.