The Vatican has approved new guidelines from Italian bishops that allow gay men to enter seminaries as long as they abstain from sex, in an unexpected adjustment to how the global Catholic Church considers possible future priests.

Although the Vatican had not explicitly barred gay men from entering the priesthood in the past, an earlier 2016 instruction had said seminaries cannot admit men who have "deep-seated homosexual tendencies".

The new guidelines, posted without fanfare on the website of the Italian bishops' conference on Thursday, say seminary directors should consider a priestly candidate's sexual preferences, but only as one aspect of their personality.

"When referring to homosexual tendencies in the formation process, it is also appropriate not to reduce the discernment to this aspect alone, but … to understand its meaning within the whole framework of the young person's personality," state the guidelines.

The Italian bishops said they approved the document in November. The text is accompanied by a note from the Vatican's clergy office, confirming the guidelines as effective for a trial period of three years.