The Catholic Church in Ireland launched a new app on Monday for young men who are thinking of joining the priesthood, taking a technological leap to reverse four decades of declining vocations.

The free "Vocations" app is designed to help users reflect on whether the clerical life is for them, including rating themselves how much they think about others, and questions about celibacy and relationships.

Launching the app, Bishop Donal McKeown admitted some people may regard it as a "churchy gimmick that will try to give the impression of modernity to something that is passe".

"I know that, for very many young people in modern Ireland, the word 'vocation' is not a meaningful term and they have little idea what clergy do, other than for an hour or two on Sundays," he said.

"But the social media is where young people are."

The number of new priests in Ireland has been declining for 40 years, not helped in recent decades by clerical sex scandals that have shocked the mainly Catholic country as well as Catholic communities across the world.

The new app offers not just questions about vocational potential, but also information about life as a priest and contact details for dioceses.

McKeown, the auxiliary bishop of Down and Connor and chairman of the bishop's Vocations Commission, admitted that he felt "a little out of his depth" being asked to launch an app.

"I may be on , but I'm a BlackBerry man myself and yesterday I had to ask a nephew -- who's a quarter of my age -- what an App is," he said.

"But I suppose it is a bit like baptising a child -- you can do something for it even if you haven't been part of its creation!"

The was designed by Father Paddy Rushe, who has been national coordinator for diocesan vocations, and developed by Dublin's Magic Time Apps.