Pope Francis is still critically ill as he battles double pneumonia, but his condition has shown a “slight improvement”, the Vatican said on Monday.

The 88-year-old pontiff is spending his 11th night in Rome’s Gemelli Hospital, making it the longest hospital stay of his nearly 12-year papacy.

“The clinical conditions of the Holy Father, in their critical nature, show a slight improvement,” the health update read.

The pope, it said, was still receiving oxygen, “although with slightly reduced flow and oxygen percentage”.

It added that the “mild kidney insufficiency,” which was first reported on Sunday, was “not a cause for concern”.

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A Vatican official, who did not wish to be named because he was not authorised to speak about the pope’s condition, earlier said that Francis was eating normally and was able to get up and move about his hospital room.

Monday’s statement said the pope had resumed work in the afternoon and in the evening made a call to the Catholic parish in Gaza, which the pope has done frequently during the Israel-Hamas war.

On Sunday, the Vatican described the pope’s condition as critical for a second day. On Saturday, it said the pope had needed a blood transfusion after experiencing a “prolonged asthma-like respiratory crisis”.

Monday’s update said the pope had not had further respiratory crises and that some of his laboratory tests “have improved”.

Double pneumonia is a serious infection that can inflame and scar both lungs, making it difficult to breathe. The Vatican has described the pope’s infection as “complex,” and said it was caused by two or more microorganisms.

Francis, who has been pope since 2013, has suffered bouts of ill health over the past two years. He is particularly prone to lung infections because he developed pleurisy as a young adult and had part of one lung removed.

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The pope’s prolonged illness has provoked an unusual amount of public speculation among Catholic cardinals, the highest ranking officials in the 1.4 billion-member church after the pontiff.