Cardinal Angelo Bagnasco chats on his mobile phone as he arrives for a meeting at the Vatican on March 8. (Dylan Martinez -- Reuters)

Eight of the cardinals who will choose the next pope are active Twitter users, but the Vatican is going to long lengths to ensure their accounts stay silent during the conclave.

On Monday, jamming devices designed to block cellphone calls, Internet signals and hidden microphones were installed inside the Sistine Chapel and nearby guest residences. WiFi will be blocked throughout Vatican City until the end of the conclave. And the conclave's active Twitter- and Facebook-users have been "forbidden access to their accounts along with all other forms of communication with the outside world," according to Catholic News Service.

"In this electronic age, I worry some cardinals may go into iPad and Twitter withdrawal," joked Sister Mary Ann Walsh, spokeswoman for the U.S. Conference of Catholic Bishops, in a blog post last week.

The strict social media lockdown isn't particularly surprising -- the conclave, which literally means "with key," has long been obsessed with secrecy. The cardinals swear an oath to that effect before even entering the Sistine Chapel, punishable by excommunication. Anyone else associated with the election, from doctors and nurses to housekeeping staff, must also swear to never tell anyone anything they hear.

Just last week, the Vatican cancelled its daily news briefings over concern there could be leaks.

But the severity of the lockdown does highlight some of the inherent tension between social media (with its ethos of transparency) and the church (which is notoriously opaque), even as the church's leaders join Twitter and Facebook.

"There is no understanding that there is another world, a network that we all live in together," Archbishop Claudio Maria Celli, one of the Vatican's social media advocates, told the Post's Jason Horowitz in February. "There isn’t this understanding.”

The eight conclave tweeters, according to CNS, are Timothy M. Dolan of New York, Sean P. O'Malley of Boston, Gianfranco Ravasi of the Pontifical Council for Culture, Odilo Scherer of Sao Paulo, Wilfrid Napier of Durban, South Africa, Lluis Martinez Sistach of Barcelona, Ruben Salazar Gomez of Bogota and Roger M. Mahony of Los Angeles. The account of a ninth conclave tweeter, Angela Scola of Milan, has recently been deleted.

Mahony, the retired archbishop of Los Angeles, has kept up an active digital presence from Rome since he arrived there in late February, updating his blog and tweeting regular Vatican updates. But even he knows better than to keep that up during conclave.