Vatican City, Mar 6 (IANS/AKI): Cardinals and translators taking part in meetings in Rome ahead of a conclave to elect Pope Benedict's successor have been sworn to silence, the Vatican said.

"You won't get any comment from me," Cardinal Severino Poletto, emeritus archbishop of Turin, told journalists at the end of the third pre-conclave meeting.

"My conscience requires this. I appreciate you need to do your job, but so do I."

The election of a pope is conducted in conditions of secrecy unique in the modern world and the threat of excommunication hangs over anyone tempted to break this silence.

No date has yet been set, but in the clearest sign so far that a papal election is nearing, the Vatican Tuesday announced the closure of the Sistine Chapel - the conclave venue - until further notice.

Vatican spokesman Federico Lombardi said work to get the chapel ready for the conclave would mainly consist in raising the floor to enable enough tables for the 115 cardinal electors to fit inside.

Two stoves need to be fitted and attached to the Sistine Chapel's chimney, one to burn used ballots and the other to send up the smoke that signals whether a new pontiff has been elected, he said.

"The smoke makes the outcome of the vote visible to the world," Lombardi said.

During the conclave, cardinals aged under 80 take part in secret votes held four times daily inside the Sistine Chapel.

The cardinals must reside within the Vatican and are not permitted any contact with the outside world.

When a candidate obtains two-thirds of the cardinal electors' votes, the smoke from the Sistine chapel's chimney turns from black to white to announce that a new pope has been chosen.