VATICAN CITY (AP) – They sat quietly on hard wooden pews, nuns in simple habits, clergymen in red-sashed cassocks, chauffeurs in sober suits, all waiting their turn to solemnly swear to keep the secrets of the papal conclave.

Housekeepers, elevator operators, waiters and other Vatican workers promised Friday never to reveal any details they might learn about the politicking and infighting that goes into the election of the pope.

No one but the 115 cardinals choosing the Roman Catholic Church’s new leader will be in the Sistine Chapel when they debate and vote during the conclave, which begins Monday afternoon. But there is a potential for Vatican workers to overhear chance remarks by cardinals between sittings.

So, with one hand on the book of the Gospels, each of several dozen Vatican officials and workers who will come in contact with the cardinals swore to keep secret anything they might learn about the conclave.

“I will observe absolute and perpetual secrecy with all who are not part of the College of Cardinal electors concerning all matters directly or indirectly related to the ballots cast and their scrutiny for the election of the Supreme Pontiff,” they intoned. “So help me God and these Holy Gospels which I touch with my hand.”

They also signed written pledges of secrecy and promised to refrain from using audio or video equipment during the closed-door votes. Violating the pledge could bring the severest of punishments the church can mete out: excommunication.

The ceremony came hours after workmen scaled the roof of the Sistine Chapel and attached the chimney pipe that will spew out puffs of white smoke to announce to the world that a new pope has been elected.

Secrecy has long been a hallmark of conclaves. But the threat of leaks and spying worries officials in an age of high-tech listening devices and with some 6,000 accredited journalists prowling Vatican City in search of what 115 red-hatted “princes of the church” are thinking.

In addition, for the first time, cardinals will be allowed to move about Vatican City freely once the voting starts, though they are forbidden to talk to anyone who hasn’t been sworn to secrecy.

Already, purported leaks from secret pre-conclave meetings are abounding in the Italian media, with newspapers reporting on the daily jockeying of factions pushing their candidates.

Early in the week, Cardinal Joseph Ratzinger was touted as the front-runner, with nearly half of the votes. By Friday, Cardinal Angelo Sodano, the No. 2 Vatican official, and Chilean Cardinal Francisco Javier Errazuriz Ossa were gaining some momentum, newspapers claimed.

The Rev. Andrew Greeley, a prominent Catholic author, said such leaks are common in the run-up to a conclave, but should dry up once the master of liturgical ceremonies cries “Extra omnes” – Latin for “all out” – and only the cardinals are left in the Sistine Chapel to vote.

“It is like the previous conclaves: About this time before they go into the conclave, the Italians begin to leak things to the Italian media and you get all kinds of wild predictions,” he said.

Pope John Paul II outlined the secrecy procedures in his 1996 document “Universi Dominici Gregis,” or “Shepherd of the Lord’s Whole Flock.”

His rules allow for a few people to have contact with the cardinals: prelates involved in ceremonial functions, maids and food servers at the Vatican hotel where the cardinals will stay, drivers who will ferry them to the Sistine Chapel and back each day, elevator operators who will take them to the chapel itself, doctors and nurses on call for sick cardinals and priests who will hear confessions.

John Paul also singled out the need for two “trustworthy technicians” who will sweep the Sistine Chapel and adjoining rooms for bugs and other listening devices. Telephones also are banned.

The document warns that any of them “who directly or indirectly could in any way violate secrecy – whether by words or writing, by signs or in any other way – are absolutely obliged to avoid this, lest they incur the penalty of excommunication.”

All those taking the oath had to be approved for their jobs by the Vatican administration and three cardinals.

The Vatican didn’t say how many affected, but official photographs of the event showed several dozen people, including nuns, prelates and lay people, waiting to take their turn in the Aula delle Benedizioni of the Apostolic Palace.

Most will only have contact with the cardinals when they are outside the Sistine Chapel, but still might learn something of what goes on inside. A food server, for example, might overhear a conversation between cardinals at dinner or an elevator operator could catch the name of a cardinal who fared well during a particular ballot.

The Vatican also released the text of a message signed by John Paul on Feb. 22, just two days before he underwent a tracheotomy to help him breathe. He died April 2 at age 84.

In the message for World Mission Sunday, John Paul urged the faithful to learn from the examples of missionaries who have been killed for their faith.

“How many missionary martyrs in our day!” it said. “The church has need of men and women willing to consecrate themselves wholly to the great cause of the Gospel.”