The cast of award-winning movie 'Conclave' have sent their well wishes to Pope Francis after it was revealed the pontiff is in critical condition in hospital as he battles pneumonia and bronchitis.

Concerns over Pope Francis' health have mounted in recent years as have questions about his succession. Here's what we know.

Pope Francis, 88, is receiving treatment at Rome's Gemelli Hospital following serious lung problems, fueling conjectures regarding the next papal election.