Vatican says pontiff's situation remains "complex" as doctors diagnose double pneumonia.

Pope Francis has shown the onset of pneumonia in both lungs, and his respiratory infection continues to "present a complex picture," the Vatican said on Tuesday evening.

A chest CT scan that the pontiff underwent on Tuesday "demonstrated the onset of bilateral pneumonia that required further pharmacological therapy," the Vatican said in a statement.

The 88-year-old pope has been suffering from a respiratory infection for more than a week and was admitted to Rome's Gemelli hospital on Friday with bronchitis symptoms.

The Vatican said on Monday that the pontiff's respiratory tract infection would require a different course of treatment and a longer hospital stay due to the "complex" clinical situation.

The latest statement on Tuesday described Francis as being in good spirits, noting that he had received the Eucharist earlier that day and had "alternated rest with prayer and reading texts". 

"He is grateful for the closeness he feels at this moment and asks, with a grateful heart, that we continue to pray for him", the Vatican concluded.

The Argentine pontiff, who had part of one lung removed in his 20s, has suffered from a string of medical ailments in recent years and was treated for bronchitis at the Gemelli two years ago.

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