The proportion of Spaniards who say they are Roman Catholic has fallen to 73 percent from around 80 percent eight years ago, according to a survey released Thursday by the CIS research centre.

About 25 percent of all Spaniards now claim to be atheists or without a religion, compared to 17 percent in 2002, the June survey of 2,500 adults found.

Only 13 percent of those questioned said they attended Mass each week compared to 20 percent eight years ago. And more than half of those surveyed, 56 percent, said they "practically never" attended Mass.

The findings reflected not just the rapid pace of secularisation the country has undergone this century but also the Roman Catholic Church's "loss of credibility", Spanish theologian Juan Jose Tamayo told radio Cadena Ser.