Pope Benedict meets Pope Francis in the Vatican,thanks him for 'mercy-filled' reign. [Photo]

Former pope Benedict XVI has thanked Francis for his 'mercy-filled' reign after the two pontiffs met in an unprecedented Vatican ceremony. 

The ceremony, in the Clementine Hall of the Apostolic Palace, featured a reigning pope honouring a retired one on the 65th anniversary of Benedict's ordination as a priest.

Francis had invited the entire Vatican Curia, or bureaucracy, to celebrate, and prelates turned out in force for the rare occasion of being able to greet each man in white.

The ceremony served in part to show continuity from Benedict to Francis amid continued nostalgia from some conservatives for Benedict's tradition-minded papacy.