The retired Pope Benedict XVI has said there is an 'inner continuity' between his pontificate and that of Pope Francis, and praised his successor as a 'man of profound philosophical and theological formation'.

The comments, aimed at contradicting conventional wisdom and misunderstandings about the two pontificates, came in a letter published by Mgr Dario Edoardo Viganò, prefect of the Secretariat for Communication, as the Vatican released a series of books on the Theology of Pope Francis, according to the Catholic Herald.

The paper reported that Benedict XVI wrote the letter in thanks for having received an advance copy of the series.

He said that it 'contradicts the foolish prejudice of those who see Pope Francis as someone who lacks a particular theological and philosophical formation, while I would have been solely a theorist of theology with little understanding of the concrete lives of today's Christian.'

The series is edited by Don Roberto Repole, the president of the Italian Theological Association.

Benedict XVI added: 'The small volumes show rightly that Pope Francis is a man of profound philosophical and theological formation. And therefore help to see the inner continuity between the two pontificates, even with all the differences in style and temperament.'

News of the letter comes on the fifth anniversary of the election of Pope Francis.