The Vatican next week will issue a document tightening the rules for creating Roman Catholic saints, a Vatican source said on Wednesday.

A 20-page document to be issued on Monday is expected to instruct bishops to be more careful and selective when starting what are knows as "causes" for sainthood.

The procedure begins at the local level when bishops start preparing evidence to support the claim of a person's sanctity and moves to the Vatican at a later stage.

Under Vatican rules, the procedure cannot even start until five years after the death of potential candidate for sainthood in order to allow time for greater reflection.

The late Pope John Paul made an exception to the five-year rule when he let the sainthood procedure for Mother Teresa of Calcutta start in India less than two years after she died in 1997.

The current pontiff, Pope Benedict, bent the rules for the sainthood process for John Paul, which was begun by the Rome archdiocese about six weeks after John Paul died in 2005.

Under the pontificate of the late Pope John Paul, the Vatican was criticised by some for having become a "saint factory".

John Paul, who reigned for nearly 27 years, beatified nearly 1,340 people and canonised nearly 500, more than all his predecessors combined since the current procedures began in 1588. Beatification is the last step before sainthood in the Roman Catholic Church.

Benedict has taken a different tack, delegating beatification ceremonies and presiding only at canonisation ceremonies, the final stage of the process.