"People hate change, but sometimes the choice is between change and a lingering death," Harper told a meeting of his diocesan synod at the beginning of June.

"There are now fewer ordained stipendiary clergy in post than ever before in the modern history of the Church of Ireland," said Harper, whose Connor diocese includes Belfast, the biggest city in British-linked Northern Ireland.

He noted that of the clergy in training, roughly one half are training for ordination to the unpaid auxiliary ministry. And amongst those currently or soon to be in training and those ordained within recent years a high proportion could be described as "late vocations", he said.

"The implication is that the length of service offered by clergy in the ordained ministry is significantly reduced," Harper said.

At the same time, demographic and other developments meant that by 2015 the church could expect to minister to an additional 105 000 people in Northern Ireland, in much smaller households than before, many consisting of only one person.

"We have inherited 19th century structures and 19th century attitudes that do not easily serve the mission of the Church in the 21st century," said Harper. He said a 10-point action plan presented to the synod would help deal with such challenges.

The Church of Ireland has parishes both in Northern Ireland and in the Republic of Ireland.

Harper's comments came as the Roman Catholic Church in Ireland, which once used to send missionaries around the world, is looking to priests from overseas to deal with what has been called a crisis in vocations among the Irish faithful.

But the Rev. Kevin Doran, director of vocations for the Catholic Church in Dublin, told the Reuters news agency, "I would warn against people making the assumption that future needs can or should be met simply by importing priests and nuns from overseas."