An Italian bishop has had to apologise to the faithful after making a simple mistake that left him snoozing his way through midnight Mass.

Mons Corrado Pizziolo, bishop of Vittorio Veneto made the dangerous decision to take a nap in his armchair after supper, ahead of the late night service on Christmas Eve.

Instead of setting his alarm for 10.50pm, the Catholic bishop accidentally cued the alert for the following morning.

He admitted his error on Christmas Day, much to the amusement of people online.

His presence was missed, particularly by those that took his absence as a sign something was gravely wrong with the religious leader.

"At a certain point I heard a knock on the door and an assistant came in, worried that I may have had a bad turn," he said.

Finally appearing at the church the following morning, for Christmas Day, he apologised to churchgoers for “almost giving them a stroke” after they became increasingly concerned about his whereabouts.

Instead, the service was taken by diocesan liturgy office chief don Mirco Miotto, ANSA reports.

A clip of the homily was broadcast on local television via La Tenda TV, amusing viewers.