Spain's traditional image as one of Europe's religious strongholds looks set to take a serious dent after it emerged that not only are half its parishes now without priests but also the average age of clerics has risen to nearly 65.

Sources inside the Catholic Church in Spain confirmed that their manpower shortage means Spanish rural priests are sometimes responsible for up to five or six parishes at a time. The most extreme case, according to El País newspaper, is a 47-year-old priest in a remote rural region of Cantabria who is responsible for 22 parishes. And a recent church-funded study has shown that in 2007, of the 23,286 parishes in Spain, no fewer than 10,615 had no priest in permanent residence.

The situation here mirrors that in some other countries. In the United States 40 years ago, there was one priest for every 772 Catholics, now it is one per 1,603. In 1970, there were 8,000 students in US seminaries, today it is around 1,300. Scotland's only seminary has announced it will close, and in Ireland the average age of priests is 63. The archdiocese of Dublin has 46 priests over 80 years of age but only two under 35.

But Spain's crisis still has the power to shock. In his keynote speech to the Spanish Ecclesiastical Congress recently, the Archbishop of Madrid, Cardinal Antonio Maria Rouco, indirectly acknowledged the problem when he said the average age of Spanish priests has risen to over 63, while in some regions it has reached 72. In Spain, the usual retirement age for men is 65.

"There are fewer of us and we are older than in previous years," Cardinal Rouco conceded – and it's a trend that looks set to continue.

Miguel Angel Morell, the head of one of three seminaries in the southern city of Granada, said: "There's been a huge drop in the number of [priestly] vocations in recent years. There are a few more young seminarists, and the ones we take are more sure of their decision, but overall the total is definitely down." The decline is steep, from 1,383 in 2008 to 1,223 this year.

The crisis is such that Barcelona, with a population of nearly three million, currently has just 30 trainee priests. Tortosa, another large city, went from having eight seminarists in 2008 to just one this year, the same total as in Zamora in north-east Spain. The diocesis of Santander had 460 priests and 430 seminarists in 1966; now it has 230 priests, including retirees, and 11 seminarists.

As for the more remote city of Soria, there are none at all. In Lerida, eastern Catalunya, the church is reported to have resorted to "importing" seminarists from South American Spanish-speaking countries to make up the shortfall.

The general lack of Spanish interest in the priesthood as a career appears to clash with the religious spectacle and fervour of the country's Holy Week processions – one of Spain's biggest tourist attractions. Preparations for the Semana Santa begin months in advance and, as early as November, large groups of strong-armed Spaniards can be seen gathering in parks and under motorway flyovers to practise lifting the huge Easter thrones that dominate the processions. The most popular of them all, in Seville, invariably brings Spain's third largest city to a standstill for days on end.

But although the Easter festivals remain immensely popular, and 73.5 per cent of Spaniards in a nationwide study in 2008 described themselves as Catholics, less than 20 per cent said they still attended mass at least once a week and a hefty 46.7 per cent said they never went at all.

The increasingly marked division between the church and Spanish society expressed itself again last week when the first draft of a new law easing access to abortion made its way through parliament. Threats by the Catholic church to excommunicate Spanish MPs who voted in favour fell on deaf ears, and the law was passed by 183 to 162.

"There is a kind of religious schizophrenia in Spain," argues Miguel Angel Morell. "People get all overcome with emotion and their tears fall when the Virgin passes by on her throne at Easter. But they're still quarrelling with their neighbours, and where's the Christian faith in that?"

As for the chronic decline in vocations, he believes that "priesthood hasn't got the social status it used to have, when the priest was someone who stood out from the crowd. On top of that, as there's only a few of us, becoming a priest nowadays involves seriously hard work. That puts some people off."

While some Spanish churches now rely on nuns from local convents and members of the congregation to help priests out, the world economic crisis has increased demands on the dwindling number that remain in active service.

"There's been no recent drop in the congregation in the cities, even if a large percentage are elderly and even if, in terms of vocations, the church is going through a kind of desert," comments Father Jose Antonio Cantos, in charge of a large urban parish in southern Spain.

"The big change for me since the economic crisis began," he says, "is the number of families coming to my church to ask for food from Caritas [a Catholic charity]. That has tripled."

Developing world: Rich countries poach from the poor

The Pope has identified the recruitment and training of priests as "top of the agenda", as ordinations and seminary admissions in the developed world dwindle. Yet while many developed nations, including the Republic of Ireland and the United States, have a shortage of priests, numbers are surging in developing countries.

Priest numbers in Asia and Africa have increased by 21 per cent and 27.6 per cent, respectively, since the turn of the Millennium, according to Vatican statistics. A spokeswoman at the National Office for Vocation, the body responsible for promoting the priesthood in England and Wales, related the figures to the stability and status afforded to Catholic priests in the developing world.

Nonetheless, in some places seminaries have been unable to keep up with resurgent church-going figures. In the Philippines, for example, where nearly 80 per cent of the population is Catholic, there is only one priest for every 10,000 Catholics, despite recent increases in the number enrolled in seminaries.

The US is increasingly recruiting aspiring priests from overseas to ease its own shortfall, worsening shortages in developing countries. In 1999, 22 per cent of newly ordained priests in the US were born overseas; by 2008, a third were foreign-born. By comparison, the Catholic church in the UK insists that any foreign-born priest aiming to join the clergy "must have been living here legally on his own resources, and have been here for a number of years for enculturation".

Greg Walton