Pope Francis has described 12 principles that guide the reform of the Roman Curia in his Christmas address to Vatican officials.

He also talked about resistance to reform, saying that while it was "healthy" to encounter difficulties, some resistance was "malicious", its "ill intentions" inspired by the Devil.

The Pope explained that his now-famous address to the Roman Curia in 2014, listing its spiritual diseases, was part of the process of reform, which relies on personal conversion.

"Every surgical operation, if it is to be successful, must be preceded by detailed diagnosis and careful analysis, and needs to be accompanied and followed up by precise prescriptions," he said.