Head of Vatican security Camillo Cibin
The Vatican says it is confident an elaborate high-tech security clampdown around the Sistine Chapel, where Roman Catholic cardinals meet starting Monday to choose a new pope, will keep their proceedings secret and the cardinals themselves cut off from the rest of the world. Technical experts have swept both the Sistine Chapel and the residence where the cardinals will stay for listening devices, and measures have been taken to neutralize incoming and outgoing mobile phone calls from both areas.

Vatican spokesman Joaquin Navarro-Vals has told reporters that Vatican security experts have taken every possible step to stop high-tech devices from eavesdropping on the voting in the Sistine Chapel. The effort comes as Vatican police try to stay one step ahead of sophisticated spying technology that did not exist when the late Pope John Paul II was elected at the last conclave in 1978.

Andrea Mergelletti, a security expert at Rome's Center for International Studies, says the Vatican is especially worried about outsiders monitoring mobile phone conversations and satellites eavesdropping from high above.

"Surely, many intelligence agencies in the world are trying to penetrate inside the Holy See," he said. "They will do [so] with special aircraft, for example, spy planes?or lasers."

Mr. Mergelletti says lasers could be pointed at the windows of the Sistine Chapel, where the cardinals will cast their votes for a new pope, or at the windows of Saint Martha House, the Vatican residence where the so-called princes of the church are staying. He says lasers can reconstruct conversations from the vibrations of windowpanes.

Although Vatican officials will not discuss details of their security operation, it has long been known that the Vatican has jamming devices to prevent eavesdropping by directional microphones. Having been spied on himself during his years as archbishop of Krakow by Poland's communist regime, Pope John Paul II issued counter-intelligence instructions for conclaves, banning mobile phones, tape recorders, radios, television sets and electronic organizers, to protect the cardinals from "threats to their independent judgment."

Security expert Mergelletti says the late pope's personal experience sensitized the Vatican to the dangers of espionage.

"I think that we now have a Holy See much less vulnerable than ever," he said.

The security technicians will continue to sweep sensitive areas until shortly before the conclave begins. They will have checked windows, doors, paintings and especially energy sources such as lamps, light fixtures, sockets, telephone plugs, fax machines and photocopiers.

Anti-bugging machines vibrate when they approach a potential listening device. But there is still some question as to whether the Vatican is able to prevent spying by laser beam. These complex eavesdropping devices work from a distance. Experts say they provide no electronic clues to security personnel that a conversation is being monitored and are undetectable by electronic sweepers.