Pope Francis, who is being treated in hospital for double pneumonia, slept well overnight and is resting, the Vatican said in a brief statement on Thursday.

The Vatican gave a largely upbeat assessment of his health on Wednesday evening, saying there had been a "further, slight improvement" in his medical condition.

It added that a "mild kidney insufficiency" reported at the weekend had been "resolved".

Wednesday's statement did not specify whether the pope was still considered to be in a critical condition, as he has been listed since Saturday. Despite the pope's improvements, it said his prognosis was still "guarded".

The 88-year-old pope is spending his 14th day at Rome's Gemelli hospital, the longest hospital stay of his papacy.