A bogus bishop nearly sneaked into the closed-door Vatican meeting of the world’s cardinals yesterday as they prepared to choose the next pope.

“Bishop Ralph Napierski” got past a checkpoint of Swiss Guards and was photographed shaking hands with Sergio Cardinal Sebastiani in the cobblestone square to the left of St. Peter’s Basilica.

But Napierski never made it inside the Pope Paul VI Audience Hall, where more than 140 cardinals from around the world were having their first formal meeting since the resignation of Pope Emeritus Benedict XVI.

What gave the gatecrasher away?

Well, his cassock was several inches too short. His crucifix looked odd. His purple sash was obviously a scarf.

And instead of wearing a zucchetto — the familiar ecclesiastical skullcap of bishops — he had a black, brimmed fedora.

Before he was hustled out of the area near St. Peter’s Square by Swiss Guards, Napierski told reporters that he was “Basilius” of the Italian Orthodox Church — which doesn’t exist.

He added that he was a founder of the Corpus Dei order — another imaginary group — and he complained that Catholic bishops had “made a mistake by moving priests” who were accused of sexual abuse from parish to parish.

Napierski, believed to be an Italian living in Germany, has a bizarre Web site in which he said he was “a slave and apostle like St. Paul” and came from “a tribe of the Roman Catholic Church” that is fighting “heresy and false movements” inside the church.

Vatican spokesman Rev. Federico Lombardi said he had no information about the incident.

Vatican officials said 107 of the 115 cardinals eligible to vote for pope attended yesterday’s meeting, but no date for the papal conclave will be set until all are in attendance.