Vatican cardinal to lead Ash Wednesday liturgy on Rome's Aventine Hill as Church marks the start of Lent.

Pope Francis, battling double pneumonia in hospital for more almost three weeks, has delegated Cardinal Angelo De Donatis to preside at the Ash Wednesday liturgy in Rome.

Ash Wednesday signifies the beginning of Lent, the 40-day period of fasting and reflection observed by Christians in the weeks leading up to Easter.

Cardinal De Donatis, Major Penitentiary, will lead the traditional celebration on the Aventine Hill on the afternoon of 5 March, the Holy See press office confirmed.

The “stational” liturgy will begin at the church of Sant’Anselmo at 16.30 before continuing with a penitential procession to the nearby Basilica of Santa Sabina where Mass will be celebrated.

Cardinals, archbishops and bishops will join the Benedictine monks of Sant'Anselmo, the Dominican priests of Santa Sabina and the faithful in the Ash Wednesday procession.

The centuries-old Roman tradition, revived in 1959 by Pope St John XXIII, is normally presided over by the pope.

On Wednesday morning the Vatican said that Pope Francis had "rested well" and resumed "non-invasive mechanical ventilation" overnight, as scheduled.

On Tuesday evening the Vatican said the pope's clinical condition remained "stable" and that he did not experience any further respiratory failure after suffering two episodes of "acute respiratory insufficiency", requiring two bronchoscopies, on Monday.

The 88-year-old pontiff has been hospitalised for almost three weeks, as prayer vigils continue outside the Gemelli Hospital and in St Peter's Square.

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