The Vatican has released the first image of Pope Francis since he was admitted to hospital a month ago.

The photo shows the pontiff sitting in a wheelchair in front of an altar at a chapel in Rome's Gemelli Hospital, where he has been recovering from pneumonia.

Earlier on Sunday, in his written Angelus message, the Pope said he faced a "period of trial" as he thanked well-wishers for their prayers, and prayed for peace in "countries wounded by war".

It marked the fifth Sunday in a row that the Pope was not present in person for his weekly blessing. The Vatican said earlier this week that an X-ray had confirmed "improvements" in his condition, but that he still needed hospital treatment.

"The Holy Father still requires hospital medical therapy, motor and respiratory physiotherapy," it said in a statement on Saturday, adding that they were "showing further, gradual improvements".

Pope Francis, 88, has not been seen in public since his admission to hospital on 14 February - and until Sunday, no photographs had been released.

"I join with so many brothers and sisters who are sick: fragile, at this time, like me," the Pope said in his latest statement, released earlier in the day.

"Let us continue to pray for peace, especially in the countries wounded by war: tormented Ukraine, Palestine, Israel, Lebanon, Myanmar, Sudan, and the Democratic Republic of the Congo."

Since his arrival in Rome's Gemelli Hospital, the Pope has been treated for double pneumonia and other infections.

He has also suffered several respiratory crises, which have raised concerns about his survival.

Earlier this month, an audio recording of Pope Francis speaking in his native Spanish was played in St Peter's Square in Vatican City.

His voice was breathless as he thanked the Catholic faithful for their prayers.

Francis, born Jorge Mario Bergoglio, is the first Pope from the Americas.

He contracted pleurisy as a young man and had a partial lung removal, which has left him particularly vulnerable to pneumonia.

As a result of his long road to recovery, there has been speculation that Pope Francis could choose to follow his predecessor Benedict XVI in resigning the papacy.

But friends and biographers close to the Pope have insisted that he has no plans to step down. And, despite his fragile health, the pontiff has continued his work from the hospital.

This year is a Catholic Holy Year, with 32 million pilgrims expected to travel to Rome.