Pope Francis today formally approved Mother Teresa's elevation to sainthood and set September 4 as the date for her canonisation.

The move comes 19 years after the death of the missionary nun who dedicated most of her adult life to working with the poor of Kolkata.

The Vatican committee that approves elevations to sainthood will meet tomorrow to consider a recommendation that becomes Saint Teresa, the Holy See announced today.

With the long-awaited decision seen as a formality, Pope Francis is expected to sign a decree approving the canonisation of the 1979 Nobel peace prize winner and set a date and venue for it to happen.

The nun and missionary will be one of five candidates for sainthood considered by the Vatican panel tomorrow but by far the most high-profile.

What is unclear is whether the pope will bow to appeals from the Catholic Church in India and travel to Kolkata for the ceremony or, as Vatican sources say is more likely, preside over one in Rome.

More than 300,000 pilgrims came to Rome in 2003 for Teresa's beatification -- the first step towards sainthood.

Known across the world, Teresa was awarded the Nobel for her work with the poor, sick, old and lonely in the slums of Kolkata.