A chest X-ray has confirmed improvements in Pope Francis’s condition in his fourth week in hospital for treatment of double pneumonia, the Vatican said on Wednesday.

Doctors have said Francis is making slow, gradual improvements and this week declared that he is no longer in imminent danger of death.

People pray for Pope Francis in front of the Agostino Gemelli Polyclinic, in Rome, where the Pontiff was admitted to hospital in early February (AP Photo/Andrew Medichini)

During his recovery, the pope continues to receive high flows of oxygen through nasal tubes during the day, and he has a non-invasive mechanical mask to aid his rest at night.

The Vatican said 88-year-old Francis again followed the Vatican’s spiritual retreat remotely and resumed physical and respiratory therapy after a quiet night.

On Thursday, Francis marks an important milestone: the 12th anniversary of his election as pope.

The Holy See has not said how the anniversary, which is a public holiday in the Vatican, might be commemorated this year.

The pope’s weekly Wednesday general audience was cancelled since the Vatican hierarchy is on retreat this week as part of the Lenten spiritual exercises that have been a mainstay of the Jesuit pope’s pontificate.

The pope’s weekly general audience was cancelled since the Vatican hierarchy is on retreat this week as part of the Lenten spiritual exercises (AP Photo/Francisco Seco)

Doctors have said Francis is making slow, gradual improvements. He was admitted on February 14 with a complex respiratory infection but doctors remain cautious, given the complexity of his condition and overall fragility, and say he needs to remain in hospital for an unspecified number of days.

Thursday marks the 12th anniversary of Francis’s election as the 266th pope. The former Cardinal Jorge Mario Bergoglio was elected on the fifth ballot of the 2013 conclave that was called after Pope Benedict XVI resigned.

While Francis has praised Benedict’s humility in stepping down and said he might follow in his footsteps, more recently, he has said the papacy is a job for life.

Another milestone comes on Friday, when Francis marks four weeks or 28 days of hospitalisation.

Francis is approaching the 12th anniversary since he was elected as the 266th pope (AP Photo/Francisco Seco)

St John Paul II has the record for a hospital stay, at 55 days in 1981 when he underwent a minor surgical operation and was then treated for a cytomegalovirus infection.

Francis is on track to equal the second-longest stay, 28 days, which John Paul recorded in 1994 when he had surgery to repair his hip joint after he fractured his right femur in a fall, according to Gemelli hospital.

The Vatican has released no photos or video of Francis since he was admitted.

The pope recorded an audio message last week to thank people for their prayers, though the weakness and breathlessness of his voice made clear how frail he was.