The Vatican has announced new rules to manage the £400,000 cost of making saints.

The announcement came shortly before Pope Francis reveals the date for the canonisation of Mother Teresa later this year.

The new norms govern the way funds for the Causes of Saints are established and managed.

They are especially relevant for the "Roman phase" of the process and the preparation of a position paper, often thousands of pages long, about the life of the candidate.

The norms demand regular and detailed accounting and disciplinary procedures in case of misuse, and ensure that spending limits are set.

Three years ago Pope Francis set up an investigation into Catholic Church finances. Among other things, the inquiry disclosed problems in the saint-making process.

Two Italian journalists subsequently published books revealing problems in the auditing process due to  lack of documents. They also disclosed the vast quantities spent by people attempting to expedite a canonisation. The journalists, Emanuele Fittipaldi and Gianluigi Nuzzi, are due to stand trial on Saturday for publishing leaked information.

The canonisation process is long and complex. Witnesses have to attest to the candidate's holiness and venerability and there are several stages, which require at least two miracles. The miracles have to be attested by doctors as genuine, and not assisted by secular medecine.