TV star Declan Donnelly says he is “heartbroken” by the death of his brother, who was a well known Catholic priest.
Father Dermott Donnelly died in hospital aged 55 after suffering a bleed on the brain.
In a tweet, ITV presenter Declan said: “We are all beyond devastated.”
In 2015 Fr Donnelly officiated at the wedding of his famous brother to Ali Astall in Newcastle in a ceremony attended by a number of celebrities.
The Diocese of Hexham and Newcastle described his death as a “great shock”.
In a statement it said: “It is with great sadness that we have to inform you of the death of Fr Dermott Donnelly who died peacefully this afternoon in hospital.
“Please pray for the repose of his soul and keep his family, especially his mother, in your prayers at this difficult time.”
Hexham and Newcastle Bishop Robert Byrne said he would be “greatly missed in the diocese for his sterling work with youth, on both a diocesan and national level”.
Messages wishing Fr Donnelly well had earlier been posted online as Catholic parishes in the north east of England announced on Facebook he had been admitted to hospital.
Fr Donnelly had been a very active supporter of the Catholic church’s official aid agency, The Catholic Agency for Overseas Development (CAFOD.).
Cafod’s head of education Monica Conmee said the charity was “hugely saddened” to hear of his death.
“Fr Dermott chose to stand in the light and, through his immense talent and gifts, so generously guided thousands of young people to experience the love and light of God in their own lives, inspiring them to share this with others,” she said.