Pope Benedict is widely expected to soon announce his first batch of cardinals, the prelates who help him run the Roman Catholic Church and act as his top advisers.

Some Vatican sources believe he may announce the names of new members of what is arguably the world's most exclusive men's club as early as tomorrow at his general audience.

The ceremony to create the cardinals, known as a consistory, is usually held a month after the Pope makes the announcement. The most likely date for a consistory could be March 25, the Feast of the Annunciation, according to Italian media reports.

There are two types of cardinals, electors and non-electors. Church rules set a ceiling of 120 "cardinal electors", who must be under 80 years old.

"Cardinal electors" can enter a conclave to elect a new Pope after a papal death. There are currently 110 cardinal electors but two men will turn 80 before the end of next month, meaning that the Pope will have enough vacancies to chose 12 "cardinal electors".

The late Pope John Paul overrode the 120 ceiling rule several times - once raising the ranks of cardinal electors to 135 - but Pope Benedict is expected to stick to the rules.

There is no limit to the number of men over 80 who a Pope can make a cardinal. Since many are retired, such appointments are often expressions of gratitude for long service or rewards for hardships endured, often in places hostile to the Church.